In particular, in LC H1299 cell lines, Ephexin1 binding to oncogenic Ras is necessary for Ephexin1 tumorigenic activity, as S16A/S18A Ephexin1 did not bind to K-Ras and did not promote anchorage-independent growth and tumor formation in mice, while S16D/S18D Ephexin1, which binds to Ras, was capable of enhancing both anchorage-independent growth in vitro and tumor growth in vivo. This evidence concerns the gene NGEF and neoplasm.