Combined inactivation of MYC and K-rasG12D in lung tumor cells results in a shutdown of Stat3 signaling.

(A) Representative phospho-Stat5 and (B) phospho-Stat3 IHC analysis demonstrates little to no levels of nuclear staining in cells following dual inactivation of MYC/K-rasG12D (n = 3 “On” & 6 “Off”) similar to conditional K-rasG12D–induced tumors. MYC/K-ras #2-3 represent independent inactivated tumors with no to highest amount of staining observed, respectively. IHC was performed similar to Figure 1D with stated antibodies with CMR-induced lung tumors that were activated or inactivated (2–11 weeks). Adjacent bar graph panels represent scoring of individual tumors for IHC staining: negative, low (<50% positive cells) or high (≥50% positive cells) for phospho-Stat5 and phospho-Stat3 positive tumors.