Exogenous NmU peptide rescues impaired BFU-E and CFU-E production from primary human CD34⁺ cells in which endogenous NmU is silenced. Human primary CD34⁺ cells nucleofected with control, NmU, or NMUR1 siRNA were cultured in methylcellulose. (A) At 24 hours after nucleofection, NmU expression was determined by quantitative real-time PCR. The data represent the mean of a triplicate determination. The frequencies of (B) CFU-GM, (C) BFU-E, and (D) CFU-E derived from control and NmU siRNA-treated CD34⁺ cells are presented from duplicate determinations from 2 independent experiments. White bars represent control siRNA-treated cells; black bars, NmU siRNA-treated cells; dark gray bars, NmU siRNA-treated cells cultured with exogenous NmU peptide; and light gray bars, NmU siRNA-treated cells cultured with exogenous neurotensin. (E) NMUR1 expression in CD34⁺ cells 24 hours after nucleofection of NMUR1 siRNA was determined by quantitative real-time PCR. The frequencies of (F) BFU-E and (G) CFU-E produced from control and NMUR1 siRNA-treated cells are presented from duplicate determinations from 3 independent experiments. The white bars represent control siRNA-treated cells; black bars, NMUR1 siRNA-treated cells; dark gray bars, NMUR1-treated cells cultured with exogenous NmU peptide; and light gray bars, NMUR1-treated cells cultured with exogenous neurotensin.