LKB1 loss confers a pro-growth signal transduction signature in ErbB2-positive mammary tumors. (A) Five NIC/LKB1+/+and five NIC/LKB1fl/fl mammary tumors were subjected to RPPAanalysis. Expression of selected proteins and phospho-proteins that are differentially expressed between NIC/LKB1+/+ and NIC/LKB1fl/fl mammary tumors. Color key indicates level of expression, with green signifying proteins and phospho-proteins that are underexpressed and red identifying those that are overexpressed compared with control cells. (B) Immunoblot analysis of mammary tumor lysates derived from NIC/LKB1+/+and NIC/LKB1fl/fl mice with antibodies directed to components of the mTOR and Akt signaling pathways. Immunoblot analysis for β-actin serves as a loading control.