RND3 (RHOE) is an atypical RHO GTPase from the RND subfamily. RND3 is constitutively bound to GTP and lacks GTPase activity. No guanine nucleotide exchange factors (GEFs), GTPase activator proteins (GAPs) or guanine nucleotide dissociation inhibitors (GDIs) act on RND3. RND3 is a direct antagonist of ROCK1 kinase activity. RND3 prevents phosphorylation of ROCK1 targets and, similar to RND1, induces stress fiber disassembly. RND3 regulates cell migration, establishment of neuronal polarity, heart development, and myometrium changes during pregnancy. Defective RND3 function is related to cardiomyopathy, hydrocephalus and cancer. Like RND1, RND3 is implicated both as a tumor suppressor and an oncogene in cancer, and can both increase and decrease sensitivity to chemotherapeutic agents, which depends on cancer type and stage. For review, please refer to Jie et al. 2015 and Paysan et al. 2016.