CD154 mRNA expression in differentiated hematopoietic cell lines. Relative CD154 mRNA levels in the indicated cell lines before and after 4-day PMA exposure in the case of K562, Meg-01, CMK, and HL-60, and before (Untx) and after (Diff) 6 hours of PMA exposure in Jurkat and Hela cells. The bars represent mean plus of minus the standard error from 3 independent experiments.