RA increases Epo production and accumulation of Epo mRNA in an oxygen-independent manner.

P19 cells were cultured with the indicated concentrations of all-trans RA for 20 hours in 21% oxygen (N) or 2% oxygen (H). (A) Epo protein (in nanograms) per milligram cellular protein is shown. (B) The ordinate shows fold induction of Epo mRNA over the control value. The Epo mRNA content when cultured without RA in 21% oxygen (N) was defined as 1. Each value is the mean ± SD of triplicate experiments.