KRAS and colon carcinoma: Following 72 hr drug exposure with equimolar concentrations of drugs (20 μM), inhibition of SMO in human colon carcinoma cell lines by GDC-0449 induced minimal cell death [36, 38, 39], while cell lines (HT29, SW480, HCT116, GC3/c1) with aberrant KRAS/BRAF signaling [51] demonstrated sensitivity to the MEK inhibitor AZD6244.