Northern blot analysis of PGI₂-R mRNA in human hematopoietic cell lines. A total of 20 μg of total RNA from respective cell lines was electrophoresed in 1.5 % agarose-formaldehyde gel and hybridized with 1.9 kb EcoRI fragment of phIPR1 for PGI₂-R cDNA. The 18S ribosomal RNA was used as the internal control. Lane 1, MOLT4; lane 2, MM-S1; lane 3, U266; lane 4, THP-1; lane 5, HL60; lane 6, KU812; lane 7, HEL; lane 8, NS-Meg; lane 9, CMK11-5; lane 10, CMK; lane 11, Meg-01; lane 12, K562; lane 13, JK-1. The experiment is representative of three performed.