To test whether other PI3K pathway alterations can induce the synergism, and whether such synergism is applicable to other cancer types, we treated glioma cancer cell line H4, lung cancer cell line NCI-H1975, and ovarian cancer cell line CAOV-3 with metformin or phenformin (when cell line is resistant to metformin), and erlotinib. Here, PIK3CA is linked to cancer.