In vitro RO4987655 effects on MAPK/PI3K pathway in NCI-H2122 ( K-ras ) cells. (a) The cells were treated with indicated concentrations of RO4987655 for 2 h. Cell lysates were analyzed by immunoblotting with antibodies to the phosphorylated versus total ERK1/2, MEK1/2, and AKT. Actin was used as a loading control. (b) Time-dependent biomarker responses of NCI-H2122 cells to RO4987655 inhibition (0.1 µM). (c) Dose-dependent anti-proliferative inhibition of RO4987655 in cells yielding a 50% inhibitory concentration (IC50) of 0.0065 µM.