PAK4 and breast cancer: As expected, the Re-Chip assays indicated that PAK4 and ERα were recruited to two ERE half sites (located at ERE1 −4099/−4096 bp and ERE2 −4087/−4084 bp) of the LIFR promoter in the presence of E2 (Fig. 6e, f), suggesting that nPAK4 regulates ERα+ breast cancer cell metastasis to the bone in part by targeting the expression of LIFR.