AXL and cancer: Axl, Met, and EGFR are highly expressed at levels on the order of 105–106 molecules/cell, consistent with values characterized previously for EGFR in cancer cell lines.44 We also found high supernatant levels of Axl and Met, ranging from ~ 1 to 6% of lysate levels shed per hour respectively, highlighting the rapid turnover of protein through proteolytic shedding.