LIN28B regulates HbF levels in cultured human cord blood erythroblasts. (A) Detection of primary let-7d miRNA in erythroblasts cultured from human CD34+ cord blood cells after RNA IP with antibodies against LIN28B or control (rabbit IgG) with DNA ladder in the right lane shown for comparison. (B) LIN28B knockdown (LIN28B-KD) confirmation by qRT-PCR quantitation of copy number per nanogram complementary DNA (cDNA) (copies/ng cDNA). LIN28B-KD and control samples were evaluated. (C) The relative expression levels of the let-7 family of miRNAs were determined by qRT-PCR. Open bars represent control samples and black bars represent LIN28B-KD. Standard deviation bars are shown. *P < .05 in triplicate experiments. Hemoglobin profiles demonstrated by HPLC analysis are shown for (D) control and (E) LIN28B-KD cultures. HbF and HbA peaks are labeled on each graph (y-axis: mVolts; x-axis: elution time in minutes). C, empty vector control; KD, LIN28B knockdown; Pri-Let7d, primary let-7d miRNA.