Interestingly, immunohistochemistry revealed that loss of LKB1 did not increase the intensity of staining for pS6 and p4E-BP1 in mammary tumors; rather the total number of cells exhibiting positive staining for mTORC1 activity markers was elevated in mammary tumors lacking LKB1 (see Additional file 8: Figure S4). Here, STK11 is linked to breast cancer.