G1-HRD-luc expression after PHZ treatment. (A) Serial imaging of G1-HRD-luc mice after PHZ treatment. Mice were treated with PHZ or vehicle on days 1 and 2. Bioluminescent images were taken of mice treated with PHZ (bottom panels) or vehicle (top panels) from day 1 to day 10. (B) Average change in the hematocrit of PHZ-treated (▴, n = 5) and vehicle-treated (⋄, n = 6) mice. (C) Average change in the photon output from PHZ-treated (▴,n = 6) or PBS-treated (⋄, n = 5) spleens. G1-HRD-luc activity on day 1 was set to 1 in each group. (D) Abundance of GATA-1 mRNA in the spleen of PHZ-treated mice (n = 4) on days 1 and 6. GATA-1 mRNA levels in the spleen were quantified by Northern blot analysis and normalized to the level of G3PDH mRNA (n = 4). (E) Induction of G1-HRD-luc activity in PHZ-treated mice from areas including femoral bone marrow (n = 4) and spleen (n = 7). Bioluminescent signals on day 6 were quantified and divided by those on day 1. (F) EPO concentrations in plasma prepared from PHZ-treated mice (n = 3) from days 1 to 7. Error bars indicate SD. *P < .05 and **P < .01 compared with untreated control.