Reticulocytosis and splenomegaly in EPO- or PHZ-treated mice and in

mk/mk mice. Wild-type animals (129sv) ormk/+ heterozygotes were treated with either EPO or PHZ. Blood samples and spleens were collected at indicated times after the last injection and also from untreated mk/mk homozygotes. Reticulocyte counts (A) and spleen index (B; SI = $100×spleen weight/body weight$⁠) were calculated for each group (2 or 5 mice in each). Results are expressed as means ± SD.