To identify the mechanistic basis of the differential dependency on the CDK4 pathway between the phenotypic epithelial and mesenchymal cancer cells, we investigated the canonical upstream survival pathways, including AKT, PIK3CA, MAPK11, and FGFR, but did not observe differential regulation between epithelial-like and mesenchymal-like cells. The gene discussed is PIK3CA; the disease is cancer.