ROBO4 and columnar cell hyperplasia of the breast: Our findings showed that silencing Robo4 to block the Slit2/Robo signaling pathway reversed the ameliorative effects of BMP-PEI-Slit2/BMMNCs transplantation on brain tissue injury and cognitive dysfunction in CCH rats, indicating that BMP-PEI-Slit2/BMMNCs functioned by activating the Slit2/Robo signaling pathway.