Although the previous studies have shown that PLD1 is involved in tumor angiogenesis14, ablation of Pld2 did not affect tumor angiogenesis (Fig. 2a): immunofluorescence staining for the endothelial cell marker CD31 and the matured blood vessel marker α-smooth muscle actin (α-SMA) revealed that the number and area of blood vessels and number of matured vessels in B16 melanoma tumors formed in Pld2−/− mice were comparable with those in wild-type (WT) mice. The gene discussed is PECAM1; the disease is melanoma.