Figure 2

Inhibitory effect of single agent and combination treatment on MAPK signaling and correlation of basal p-MEK level with the synergistic effect of PRi and MEKi combination. A, B and C) Western blot analysis of NRAS mutant cell lines treated for 24 hours with DMSO, or 500 nM of PRi (A) or 25 nM of MEKi (B) or combination of 500 nM of PRi and 25 nM of MEKi (C). The included heat maps were generated from log2 of IC50s (from Figure 1B) to indicate the cell lines responses across all the treatments ranging from the most sensitive (green) to the most resistant (red). D) Relative p-MEK levels of NRAS mutant cell lines were quantified from the intensity of untreated bands on Figure 2B. The reference band (Ref.) is the untreated M207 that was used for the normalization of values between the blots. E) Reverse correlation (Spearman’s Rank analysis, ρ = −0.7, p = 0.02) between the CI ranking (Figure 1C) and the ranking of p-MEK levels, indicating that the cell lines with higher levels of p-MEK exhibit higher synergistic effects with the combination treatment.