Figure 2.

HIF-1a does not affect TGF-b1 secretion in human fibroblasts at 1% or 2% hypoxia or reoxygenation. Human fibroblasts were incubated at 20% O₂, 1 % O₂, or 1 % O₂ for 24 h, followed by reoxygenation for 1 or 3 h. (A) Equal amounts of cell culture supernatants from these were used to measure TGF-β1 levels using ELISA. Error bars on the graph indicate standard deviation from the mean (n = 2). (B) Equal amounts of cell lysates from the experiment in (A) were separated on an SDS-PAGE gel and probed for HIF1α levels. Tubulin was probed as loading control (immunoblot below). While HIF1α increased with hypoxia and decreased following reoxygenation, no change was observed in TGF-β1 levels. (C) Similarly, fibroblasts were incubated at 20% O₂, 2 % O₂, or 2 % O₂ for 24 h, followed by reoxygenation for 1 h, and probed for HIF1α levels. HIF1α was not present at 2% hypoxia.