CXCL12 and bone neoplasm: Thus, to determine the role of PI4KA in CXCL12/CXCR4 signaling contributing to bone tumor growth, we have developed stable knockdown of PI4KA in PC3-CXCR4 and C4-2B cell with two independent PI4KA shRNA (#27 and #30) through lentiviral transduction.