Stable shRNA knockdown of Axl significantly reduces tumour growth in a xenograft model of breast carcinoma [65], and inhibition of Axl with siRNA in human umbilical vein endothelial cells blocks endothelial tube formation in vitro, suggesting that inhibition of Axl may restrict the angiogenesis required for breast tumour cell growth [79]. Here, AXL is linked to breast carcinoma.