The soluble nectin-4 ectodomain, which could be detected in the sera of breast cancer (37), lung cancer (9), and ovarian cancer (11, 38) patients, has been shown to interact with endothelial integrin β4 to promote angiogenesis in breast cancer through the Src-regulated PI3K/Akt pathway (19). The gene discussed is SRC; the disease is breast carcinoma.