PTK2 and breast cancer: We also tested the effects of ligand-activated PPARγ on CXCR4 downstream signaling pathways and we found decreased levels of phosphorylated FAK, AKT and ERK1/2 upon BRL treatment which was reversed in presence of GW, confirming that BRL reduces the CXCR4 signaling in a PPARγ-dependent manner in both breast cancer cell lines (Figure 4D).