While there were no measurable alterations in pericyte accumulation in the vasculature of RIP-Tag2; Arf−/− angiogenic lesions, the possibility remains that the initial recruitment of Pdgrβ+ perivascular cells to the neovasculature could be stimulated either directly or indirectly (e.g. via secretion of an as yet to be identified pro-angiogenic factor from Arf-null pre-neoplastic/tumor cells) by loss of Arf. Here, CDKN2A is linked to neoplasm.