Figure 1. Lin28 physically associates with BMP4 mRNA in Lin28-expressing cells. (A) BMP4 mRNA is enriched in Lin28-containing RNPs in human ES cells as revealed by IP and deep sequencing.¹⁹ RNA-Seq libraries were generated using RNAs captured by IP using anti-Lin28 or preimmune IgG. The libraries derived from Lin28 IP and preimmune IP samples were individually used for sequencing on an Illumina GAII platform. Approximately 10 million 75-nt reads were obtained from each IP sample, and these sequences were uniquely aligned to a combined database of the human genome and splice junctions, and these read counts were further analyzed using normalized values to identify transcripts that were significantly different between the Lin28 IP and preimmune IP samples. The heights of the peaks indicate frequencies of the 75-nt sequence reads that match the particular exon regions of the genome marked as blue boxes at the bottom of the histograms. (B and C) BMP4 mRNA was enriched in Lin28-containing RNPs in PA-1 (B) and IGROV1 (C) cells by IP, followed by RNA extraction and RT-qPCR analysis. Relative abundance of the indicated mRNAs present in the anti-Lin28 vs. preimmune IP complexes are shown as relative fold enrichment. Error bars are mean ± SD (n = 3).