AXL and prostate cancer: To determine the role of Axl in tumor cell metastatic phenotypes, human breast (MDA-MB-231) and prostate cancer cell lines (PC3ML and DU-145) were transduced with lentiviral shRNA against scrambled non-target sequence (shSCM) or AXL (shAXL), and the transduction efficiency was confirmed by Western Blot (Fig. 1a–c).