diff --git a/src/mavedb/lib/validation/constants/general.py b/src/mavedb/lib/validation/constants/general.py
index 22ca4cbf5..e78d4de53 100644
--- a/src/mavedb/lib/validation/constants/general.py
+++ b/src/mavedb/lib/validation/constants/general.py
@@ -44,6 +44,7 @@
 variant_count_data = "count_data"
 required_score_column = "score"
 
+multi_value_keys = ["molecular mechanism assessed"]
 calibration_variant_column_name = "variant_urn"
 calibration_class_column_name = "class_name"
 
diff --git a/src/mavedb/lib/validation/keywords.py b/src/mavedb/lib/validation/keywords.py
index 305a7c5aa..237804f1c 100644
--- a/src/mavedb/lib/validation/keywords.py
+++ b/src/mavedb/lib/validation/keywords.py
@@ -1,5 +1,6 @@
 from typing import Optional
 
+#from mavedb.lib.validation.constants.general import multi_value_keys
 from mavedb.lib.validation.exceptions import ValidationError
 from mavedb.lib.validation.utilities import is_null
 
@@ -7,7 +8,7 @@
 def validate_code(key: str, label: str, code: Optional[str]):
     # TODO(#511) Re-enable the Gene Ontology code requirement.
     pass
-    # if key.lower() == "phenotypic assay mechanism" and label.lower() != "other":
+    # if key.lower() == "molecular mechanism assessed" and label.lower() != "other":
     #     # The Gene Ontology accession is a unique seven digit identifier prefixed by GO:.
     #     # e.g. GO:0005739, GO:1904659, or GO:0016597.
     #     if code is None or not re.match(r"^GO:\d{7}$", code):
@@ -29,6 +30,14 @@ def validate_duplicates(keywords: list):
         keys.append(k.keyword.key.lower())  # k: ExperimentControlledKeywordCreate object
         if k.keyword.label.lower() != "other":
             labels.append(k.keyword.label.lower())
+        # TODO: When molecular mechanism assessed has one GO with one key, we'll available this validator.
+        # Currently molecular mechanism assessed has combined GO terms in value.
+        # key = k.keyword.key.lower()
+        # label = k.keyword.label.lower()
+        # if key not in multi_value_keys:
+        #     keys.append(key)
+        # if label != "other":
+        #     labels.append(label)
 
     keys_set = set(keys)
     labels_set = set(labels)
diff --git a/tests/helpers/constants.py b/tests/helpers/constants.py
index e06d07a12..b47946e4f 100644
--- a/tests/helpers/constants.py
+++ b/tests/helpers/constants.py
@@ -430,19 +430,26 @@
     },
     {"key": "Delivery Method", "label": "Other", "special": False, "description": "Description"},
     {
-        "key": "Phenotypic Assay Mechanism",
+        "key": "Molecular Mechanism Assessed",
         "label": "Other",
         "code": None,
         "special": False,
         "description": "Description",
     },
     {
-        "key": "Phenotypic Assay Mechanism",
-        "label": "Label",
+        "key": "Molecular Mechanism Assessed",
+        "label": "Sodium channel activity",
         "code": "GO:1234567",
         "special": False,
         "description": "Description",
     },
+    {
+        "key": "Molecular Mechanism Assessed",
+        "label": "Calcium-mediated signaling",
+        "code": "GO:1134567",
+        "special": False,
+        "description": "Description",
+    },
     {
         "key": "Phenotypic Assay Profiling Strategy",
         "label": "Shotgun sequencing",
diff --git a/tests/routers/test_experiments.py b/tests/routers/test_experiments.py
index 17ab2ab9d..08b42298f 100644
--- a/tests/routers/test_experiments.py
+++ b/tests/routers/test_experiments.py
@@ -524,8 +524,8 @@ def test_create_experiment_that_keyword_gene_ontology_has_valid_code(client, set
         "keywords": [
             {
                 "keyword": {
-                    "key": "Phenotypic Assay Mechanism",
-                    "label": "Label",
+                    "key": "Molecular Mechanism Assessed",
+                    "label": "Sodium channel activity",
                     "code": "GO:1234567",
                     "special": False,
                     "description": "Description",
@@ -537,8 +537,8 @@ def test_create_experiment_that_keyword_gene_ontology_has_valid_code(client, set
     response = client.post("/api/v1/experiments/", json=experiment)
     assert response.status_code == 200
     response_data = response.json()
-    assert response_data["keywords"][0]["keyword"]["key"] == "Phenotypic Assay Mechanism"
-    assert response_data["keywords"][0]["keyword"]["label"] == "Label"
+    assert response_data["keywords"][0]["keyword"]["key"] == "Molecular Mechanism Assessed"
+    assert response_data["keywords"][0]["keyword"]["label"] == "Sodium channel activity"
     assert response_data["keywords"][0]["keyword"]["code"] == "GO:1234567"
 
 
@@ -547,7 +547,7 @@ def test_create_experiment_that_keyword_gene_ontology_is_other_without_code(clie
         "keywords": [
             {
                 "keyword": {
-                    "key": "Phenotypic Assay Mechanism",
+                    "key": "Molecular Mechanism Assessed",
                     "label": "Other",
                     "code": None,
                     "description": "Description",
@@ -560,17 +560,60 @@ def test_create_experiment_that_keyword_gene_ontology_is_other_without_code(clie
     response = client.post("/api/v1/experiments/", json=experiment)
     assert response.status_code == 200
     response_data = response.json()
-    assert response_data["keywords"][0]["keyword"]["key"] == "Phenotypic Assay Mechanism"
+    assert response_data["keywords"][0]["keyword"]["key"] == "Molecular Mechanism Assessed"
     assert response_data["keywords"][0]["keyword"]["label"] == "Other"
 
 
 # TODO(#511) Re-enable the Gene Ontology code requirement.
+# def test_create_experiment_that_keywords_has_multiple_molecular_mechanism_assessed_labels(client, setup_router_db):
+#     valid_keywords = {
+#         "keywords": [
+#             {
+#                 "keyword": {
+#                     "key": "Molecular Mechanism Assessed",
+#                     "label": "Sodium channel activity",
+#                     "code": "GO:1234567",
+#                     "special": False,
+#                     "description": "Description",
+#                 },
+#             },
+#             {
+#                 "keyword": {
+#                     "key": "Molecular Mechanism Assessed",
+#                     "label": "Calcium-mediated signaling",
+#                     "code": "GO:1134567",
+#                     "special": False,
+#                     "description": "Description",
+#                 },
+#             }
+#         ],
+#     }
+#     experiment = {**TEST_MINIMAL_EXPERIMENT, **valid_keywords}
+#     response = client.post("/api/v1/experiments/", json=experiment)
+#     assert response.status_code == 200
+#     response_data = response.json()
+#     assert len(response_data["keywords"]) == 2
+#     labels = {kw["keyword"]["label"] for kw in response_data["keywords"]}
+#     codes = {kw["keyword"]["code"] for kw in response_data["keywords"]}
+#     keys = {kw["keyword"]["key"] for kw in response_data["keywords"]}
+#
+#     assert keys == {"Molecular Mechanism Assessed"}
+#     assert labels == {
+#         "Sodium channel activity",
+#         "Calcium-mediated signaling",
+#     }
+#     assert codes == {
+#         "GO:1234567",
+#         "GO:1134567",
+#     }
+
+
 # def test_cannot_create_experiment_that_keyword_has_an_invalid_code(client, setup_router_db):
 #     invalid_keyword = {
 #         "keywords": [
 #             {
 #                 "keyword": {
-#                     "key": "Phenotypic Assay Mechanism",
+#                     "key": "Molecular Mechanism Assessed",
 #                     "label": "Label",
 #                     "code": "invalid",
 #                     "description": "Description",