Hybrid cell line (MO3.13) that expresses phenotypic characteristics of primary oligodendrocytes in an immature developmental stage and rat oligodendrocyte precursor cells were incubated with sPIF (100 and/or 200 nM or control — Ctrl). RNAs and proteins were extracted 48 hours later, and levels were determined by qRT-PCR (A and C) and Western blots (B and C: representative Western blots). (D and E) Cells were transfected with control siRNA (siCtrl) or siRNA specific for H19 (siH19) or incubated with sPIF at 100 and/or 200 nM or Ctrl. RNAs were harvested 48 hours after transfection and analyzed by qRT-PCR. (F) Cells were transfected with control siRNA (siCtrl) and/or control miRNA (siCon) and siRNA specific for H19 (siH19) or let-7 inhibitor (iLet7), and RNAs were harvested 48 hours after transfection and analyzed by qRT-PCR. Results are presented as mean ± SEM and are representative of at least 3 independent experiments. Single comparisons with Ctrl were made using a 2-tailed Student’s t test or Mann-Whitney test with Bonferroni’s correction. **P < 0.005; ***P < 0.0005. The levels of Ctrl and siCtrl were arbitrarily set to 1. Protein levels are presented after normalization to actin. Each experiment was conducted at least 3 times.