KRAS and non-small cell lung carcinoma: To address the contribution of ERK activity to clonogenic survival of K-ras mutant NSCLC cells, we pre-treated A549 or H2009 cells with the MEK inhibitor, PD98059, either during plating and clonogenic growth (Figure 5C and 5D, “P”), during suspension prior to plating (Figure 5C and 5D, “S”), or during both phases (Figure 5C and 5D, “P+S”).