EPO and anemia (phenotype): This evidence was not, however, in accordance with a previous study which showed that the number of Epo-TAg (a genetic marker for cortical interstitial fibroblasts) expressing fibroblasts is reduced in the injured kidney, but upon intense stimulation such as severe anemia or hypoxia, there was a greater increase in Epo-TAg expressing fibroblasts in the injured kidney which consequently narrowed the disproportion between the injured and uninjured kidney.