CDC42 and neoplasm: Steroidogenic acute regulatory protein-related lipid transfer domain-containing protein 13 (StarD13) is a GAP for RhoA and Cdc42 with potential tumor suppressor functions (Ching et al., 2003; El-Sitt and El-Sibai, 2013; El-Sitt et al., 2012; Ullmannova and Popescu, 2006).