RABGEF1 and neoplasm: In addition, Rabex-5 and Rabaptin-5 have been shown to function as neoplastic tumor suppressors and are implicated in human cancers (Magnusson et al., 2001; Wang et al., 2009; Christoforides et al., 2012; Thomas and Strutt, 2014), and Rabex-5 has also been shown to determine the neurite localization of its substrate Rab proteins and thus plays an important role in the development of hippocampal neurons (Mori and Fukuda, 2013; Mori et al., 2013).