EGFR and neoplasm: In both tumor models, neither EP nor aderbasib had any effect on the expression or phosphorylation of the proteins analyzed, but combining aderbasib with EP and PEPDG278D caused profound loss of both expression and phosphorylation of EGFR and HER2, loss of phosphorylation but not expression of all other RTKs and downstream signaling proteins analyzed, including HER3, IGF1R, MET, SRC, AKT, ERK, and MEK, loss of expression of NRAS and HRAS, and activation of caspase 3 (Fig. 5c).