ROBO2 and hepatocellular carcinoma: Next, we detected the cell cycle in HCC cells with Robo2 knocking down and/or YB-1 over-expressing by flow cytometry, and verified that knocking down Robo2 caused G1 phase cells to increase and S phase cells to decrease; over-expression of YB-1 alone could increase the percentage of S-phase cells and decrease the percentage of G1-phase cells; and over-expression of YB-1 further weakened the cell cycle change induced by knocking down Robo2 (Fig. 5E, F), which indicated that YB-1 suppressed G1/S cell cycle arrest induced by knocking down Robo2 in HCC cells.