Hypoxia induces VEGF protein expression in CAFs. Evaluation of VEGF expression by immunofluorescence assays. CAFs were treated for 12 h with vehicle (a2) or 100 μM CoCl2 (a3), or cultured under normoxia (b2) or low oxygen tension (2% O2 for 12 h) (b3), as indicated. VEGF accumulation is evidenced by the green signal. Nuclei were stained by DAPI (blue signal) (a1, b1). For descriptive purposes, each side panel shows the plot profiles obtained at the level of the yellow line of the corresponding inset using the program WCIF Image J for Windows. Note the higher values indicating zones of intense labeling. Images shown are representative of 20 random fields of three independent experiments.