JJ cells were cultured in hypoxia after transfection with CXCR4 siRNA or control siRNA. (A)VEGFA and CXCR4 mRNA were quantified relative to 18S with real-time PCR as described in Material and Methods. (B) CXCR4 was evaluated with Western blot and VEGFA in conditioned media with ELISA (C). (D) HUVEC were cultured with conditioned media from JJ cells and length of tubular structures measured after twenty-four hrs. (E, F) Representative bright field images are shown. Data are shown as mean ± SD for three replicates (A,C) and four replicates (D). * < 0.01, # p < 0.0001; ** p < 0.02. Scale bar, 100 μm. Con-si: control siRNA, CXCR4-si: CXCR4 siRNA.