AKT1 and colorectal carcinoma: Finally, as irinotecan induces AKT and MEK phosphorylation in CRC cells (Fig. 1c), the interaction of the SN38, BKM120-MEK162 combination was evaluated in HCT116 cells using the SRB cytotoxicity assay and a three-dimensional dose matrix with increasing doses of the three drugs (five doses for BKM120, five doses for MEK162 and one dose for SN38) (Fig. 6a).