IL13RA2 and melanoma: Although the loss of IL13Rα2 expression in A375 cells did not affect in vitro proliferation (Fig. 5B), tumours formed after the subcutaneous inoculation of the A375-IL13RA2 KO cells were significantly smaller than those derived from the control cells (Fig. 5C,D), suggesting that endogenous IL13Rα2 expression in A375 melanoma cells is necessary for in vivo tumour formation.