AXL and neoplasm: We tested the cytotoxic potential of Axl inhibition using R428, an Axl-specific small molecule inhibitor with proven anti-tumour efficacy in vitro and in vivo.34 Using SRB assays, we confirmed R428 to exert growth inhibitory effects in the micromolar range across a panel of HCC cell lines after 72 h of continuous exposure to the drug (Fig. 2a).