miR-24 directly downregulates six transcription factors. A: 3′UTR sequences of the six transcription factors predicted to include miR-24 MREs were aligned with miR-24, and both WT and mutant sequences are listed. B: Luciferase reporter activities analyzed as above of WT gene promoters were significantly repressed by elevated miR-24, whereas those of the mutant gene promoters were reversed to the normal level (**P < 0.01 vs. vector; ##P < 0.01 vs. wt). C: mRNAs analysis showed that only Neurod1 and Pdx1 were slightly downregulated, but others were not altered (**P < 0.01 vs. actin). D: Conserved miR-24 binding sites in the 3′UTR of Neurod1 from mouse and human. E: Full-length 3′UTR sequence of mouse Neurod1 was inserted downstream of a reporter gene, and point mutation of the miR-24 seed pairing sequence was generated using the QuikChange Site-Directed Mutagenesis kit. miR-24 inhibited the luciferase activity of WT Neurod1, whereas those of the mutant construct and vector control were indistinguishable from each other (**P < 0.01 vs. vector+pre–miR-24; ##P < 0.01 vs. wt-Neurod1+pre–miR-24). F: miR-24 (50 nmol/L) apparently decreased the Neurod1 protein level starting from 48 h. G: miR-24 at both 10 and 50 nmol/L were sufficient to repress Neurod1 protein production.