CXCR4 expression in PICP-treated and untreated contro-lateral tumors. Micrographs are representative of the results obtained from the analysis of at least two series of contro-lateral tumors treated or untreated with PICP. On the top is indicated the day after implant when the tumors were explanted. The two topmost rows are analysis by ISH and the two lower rows are analysis by immunoperoxidase for CXCR4. Bar is 25 μm.