Effect of KRAS knockdown on viability of cells harboring a KRAS mutation. (A) KRAS mutant or (B) KRAS wild-type cells were selected for KRAS knockdown. Scatterplots indicate that these lines show variable sensitivity to MEK inhibition. The Y-axis shows RAS siganture score, and the X-axis show cell sensitivity to MEK inhibition. Lower numbers on the X-axis indicate increasing sensitivity. Cell lines in red text were treated with siRNAs targeting KRAS. Western blots were performed for KRAS and B-actin. Control = Dharmacon non-targeting siRNA pool; KRAS = siRNA targeting KRAS, none = no transfection. Bar charts show viability as measured by the ATP vialight assay. The percent viability relative to the control siRNA is shown. R = Pearson correlation coefficient, p = the corresponding P-value.