LIN-28: a potential miRNA target in P19 and NT2/D1 cells. (a) Western blot of LIN-28 protein in P19 and NT2/D1 cells treated with RA at day 0. Actin is shown as loading control for protein concentration. (b) Depiction of 3' UTR of mouse Lin-28 mRNA, colored blocks indicated strong sequence homology with human Lin-28 3' UTR. Colored bars indicate predicted miRNA sites on Lin-28 3' UTR conserved blocks. Insets of block 2 and block 3 show predicted RNA-RNA interaction of Lin-28 3' UTR and RA-induced let-7a, miR-125b, and miR-218.