AXL and neoplasm: However, when 5 × 104 cells (clone 2.2) were transplanted into the mammary fat pad of an immune-competent BALB/C host, AXL KO showed impaired tumor growth (50 % less tumor volume, Fig. 2f), which correlated with less metastasis (50 % less metastatic burden in the lungs, Fig. 2g, h).