CXCR4 expression in different colon cell lines cultured in hypoxia. (A) Transcript CXCR4 expression in normoxia (20% O2) and hypoxia (1% O2) in SW480, HCT116 and HT29 cell lines. (B) Transcript CXCR7 expression in normoxia (20% O2) and in hypoxia (3% and 1% O2) in SW480 cell line. Trancript HIF-1α (C) and CXCR4 (D) expression after siRNA #1 or #2 anti-HIF-1α transfection; * p = 0.015; ** p = 0.001.