diff --git a/moto/apigateway/models.py b/moto/apigateway/models.py
index 6585d19f..bfcfdbfa 100644
--- a/moto/apigateway/models.py
+++ b/moto/apigateway/models.py
@@ -339,9 +339,11 @@ class RestAPI(object):
         return status_code, {}, response
 
     def update_integration_mocks(self, stage_name):
-        stage_url = STAGE_URL.format(api_id=self.id.upper(),
+        stage_url = STAGE_URL.format(api_id=self.id,
             region_name=self.region_name, stage_name=stage_name)
-        responses.add_callback(responses.GET, stage_url,
+        responses.add_callback(responses.GET, stage_url.upper(),
+                               callback=self.resource_callback)
+        responses.add_callback(responses.GET, stage_url.lower(),
                                callback=self.resource_callback)
 
     def create_stage(self, name, deployment_id, variables=None, description='', cacheClusterEnabled=None, cacheClusterSize=None):