Similarly, treatment of U251, T98G and C6 glioblastoma cells with temsirolimus (an inhibitor of mTOR kinase), U0126 (an inhibitor of MEK1/2 kinases), and temozolomide (a DNA alkylating agent) have shown unpredictable results when the MTT assay was used for measuring cytotoxicity3. The gene discussed is MAP2K1; the disease is glioblastoma.