EPOR and GATA-1 gene expression depends on the cell-cycle event. (A) Northern blot analysis of EPOR, GATA-1, and GATA-2 mRNA levels. Log phase-growing UT-7 cells were fractionated according to cell-cycle phase by centrifugal elutriator. Then each RNA was isolated from the fractionated cells. (B) Densitometric analysis of the data presented in (A). The amount of RNA loaded in each lane was assessed by the intensity of the 28S ribosomal RNA bands. The data show the relative ratio of the amount of mRNA in G₀/G₁ or S phase to that of G₂/M phase. (C) ³H-thymidine incorporation into the cells used for Northern blot analysis above.