Expression of intron VII–spliced and –unspliced mRNAs for EPOR in peripheral blood (A, B, D, and E) and bone marrow (C) mononuclear cells from PV patients, normal volunteers, ET and CML-CP patients, and a cell line. Total cellular RNA was reverse-transcribed and subjected to PCR using the primer sets of sense-3 and antisense-3, and then sense-4 and antisense-4 (nested PCR, [A]) or sense-2 and antisense-2 (B, C and D), respectively. In (E), cytoplasmic RNA was reverse-transcribed and subjected to PCR using the primers sense-2 and antisense-2. (A) Lane a, PV patient no. 1; b, PV patient no. 3; c, normal no. 1 (RNA lot 1); d, normal no. 1 (RNA lot 2); e, normal no. 2. The size of the intron VII–spliced and –unspliced mRNAs is 670 bp and 765 bp, respectively. (B) Lane a, PV patient no. 4; b, PV patient no. 5; c, PV patient no. 6; d, normal no. 4; e, cell line KBM-5. (C) Lane a, normal volunteer no. 3; b, PV patient no. 2; and c, PV patient no. 1. (D) Lane a, ET no. 1; b, ET no. 2; c, CML-CP no. 1; d, CML-CP no. 2; e, CML-CP no. 3. (E) Lane a, PV patient no. 7; b, PV patient no. 8; c, normal no. 5; d, normal no. 6; and e, negative control without template. In (B) to (E), the sizes of intron VII–spliced and –unspliced mRNAs are 236 bp and 331 bp, respectively.