Fig 1: Hypoxia upregulates AK4 in an HIF-1a-dependent manner. (A) Representative Western blot for HIF-1a and AK4 followed by densitometric quantification of relative expression in PASMCs treated with 50 µM DFO for 24 h, compared to untreated control; n = 4. (B) Representative Western blot for HIF-1a and AK4 and densitometric quantification of relative expression in PASMCs transfected with HIF-1a siRNA (siHIF-1a), followed by hypoxic (HOX, 1% O2) exposure for 24 h, compared to non-targeting siRNA as a control (scrambled siRNA = scramble) under NOX or HOX; n = 3. (C,E) Relative mRNA expression of AK4 in PASMCs transfected with siHIF-1a (C) or siEPAS1 (E), followed by hypoxic (HOX, 1% O2) exposure for 24 h, compared to control (scramble); n = 3–5. (D) Representative Western blot for EPAS1 (HIF-2a) and AK4 and densitometric quantification of relative expression in PASMCs transfected with EPAS1 siRNA (siEPAS1), followed by hypoxic (HOX, 1% O2) exposure for 24 h, compared to control (scramble) under NOX or HOX; n = 4. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p< 0.0001, (A,C,E) unpaired Student’s t-test or (B,D) one-way ANOVA followed by Tukey multiple comparisons test.