Thus, both gain- and loss-of-function mutations in specific RHO GTPase pathway genes have been detected in human tumors, with some RHO proteins and their signaling components unexpectedly acting as tumor suppressors in certain contexts (e.g., the RHO GEFs VAV1 and TIAM1) (Bustelo, 2018; Zandvakili et al., 2017; Svensmark and Brakebusch, 2019; Porter et al., 2016; Robles-Valero et al., 2017; Hord et al., 1997; Uhlenbrock et al., 2004; Malliri et al., 2006; Yu et al., 2013; Diamantopoulou et al., 2017). This evidence concerns the gene RHO and neoplasm.