CoCl2 induces HO-1–DsRed expression through the NRF2 pathway. Thioglycolate-induced peritoneal macrophages were isolated from HO-1DsRed/+ and Nrf2−/−::HO-1DsRed/+ mice. Representative images (A, C, and E) and relative DsRed fluorescence intensity (B, D, and F) in macrophages after 48 h of treatment with CoCl2 (A and B), hypoxia (1% O2) (C and D), or the PHD inhibitor 50 μM GSK360A (E and F). Scale bar, 200 μm.