Involvement of HIF-1α and GPER in hypoxia-induced expression of CTGF and migration of CAFs. (a) The mRNA expression of CTGF is induced after the stimulation of CAFs with 100 μM CoCl2, as indicated. Values are normalized to the 18S expression and shown as fold changes of mRNA expression induced by CoCl2 compared to cells treated with vehicle. The protein expression of CTGF is induced by 100 μM CoCl2 (b) or low oxygen tension (2% O2, for 4 h) (c). The up-regulation of CTGF protein expression observed upon 100 μM CoCl2 treatment is abrogated silencing HIF-1α (d) or GPER (e) expression. The migration of CAFs induced by hypoxia (2% O2, for 6 h) is prevented knocking down HIF-1α and GPER expression. Cell migration is rescued in CAFs transfected with shGPER, exposed to hypoxia (2% O2, for 6 h) and treated with 100 ng/ml CTGF (f). Results shown are representative of three independent experiments. Side panels show densitometric analysis of the blots normalized to β-actin. (○) P < 0.05 for cells receiving vehicle (-) or cells cultured under normoxia versus CoCl2 treatment or cells cultured under hypoxia.