RAC1 and cancer: To explore whether miR-675-5p exerts its functions through the REPS2/RalBP1/RAC1/CDC42 signaling pathways that contribute to cancer proliferation, development and progression [27–29, 31], we examined a number of the main REPS2 signaling downstream target genes, including RalBP1 which possessed GAPase activity, RAC1 and CDC42 with GTPase activity, MMP9 and MMP2 which were demonstrated to be associated with tumor dissemination and metastasis and Cyclin D1 correlated with G1-S phase transition.