PTEN and neoplasm: We have shown previously that overexpression of EphB4 in tumour cells is tightly regulated by known transforming agents such as EGFR (Masood et al, 2006) and HER-2/neu (Kumar et al, 2006), and inhibited by tumour suppressors such as p53 (Xia et al, 2006) and PTEN (Xia et al, 2005).