Effect of recombinant human erythropoietin and hypoxia on the proliferative potential of human renal cell lines. A, Western blot analysis of four human renal cell lines was done to confirm EPO and EPOR status. Furthermore, other key molecules (e.g., VHL, HIF-1α, HIF-2α and VEGF) related to clear cell RCC were noted. Cells were grown in complete media in normoxic condition and total cellular protein lysate in the exponential phase were collected for analysis. B, Western blot analysis of four human renal cell lines exposed to hypoxia for 6 and 24 hrs was perform to note any change in the molecular status evident from normoxic conditions. β-actin is used as a loading control. C, Proliferation rate was measured in four human renal cell lines cells exposed to normoxia or hypoxia and grown in the indicated doses of recombinant human EPO (0–50 units/mL) at 48 hrs. Data were represented as mean ± SD relative to untreated cells, which are set to 100%. Three independent experiments were performed in triplicate. Significance compared to untreated cells is denoted by *, p < 0.05; **, p < 0.01, ***, p < 0.001.