Fig. 1.

RTK activation in malignant cells and possibility for the combined therapy. a The constitutive, ligand-independent, catalytic activation of RTK under pathophysiological conditions leads to uncontrolled cell proliferation as well as increased cell survival and metastasis. b Blocking RTK function with inhibitors (orange blocks) activates a bypass mechanism that involves the induction of autophagy, which may contribute to the acquisition of drug resistance. c The enhanced efficacy of combination approaches (RTK inhibitors and autophagy inhibitors, such as chloroquine (CQ) or 3-methyladenine (3-MA); yellow blocks) with respect to a single RTK-targeted strategy suggests this method as more promising strategy for the elimination of tumor cells