Types of globin mRNA expressed in Epo-stimulated EpoR⁺ clones of Ba/F3 and B6SUtA cells analyzed by RNase protection assays. Total cellular RNA (10 μg) was hybridized separately with a mixture of ɛ, βh1, and β^maj/minprobes and with a mixture of ζ, -1/-2, and actin probes. Ba-ER-1 to -2 and B6-ER-1 to -2 are described in Fig 1. RNA from DBA/2 mouse day 11.5 embryonal blood (d11.5 emb, lane 1) served as controls for embryonal globin mRNAs. Molecular weight markers (MWM, lane 8) are Sau3A-digested ³²P-labeled pUC19 DNA.