Figure 6.

Model schematic integrating retinoic acid (RA) signaling with other pathways dependent on PROP1. In this study, we show that PROP1 is required for proper Aldh1a2 expression and RA signaling during embryonic pituitary development, although we do not yet have evidence of whether PROP1 direct or indirectly regulates Aldh1a2 gene expression. RA signaling is required for timely expression of lineage markers and pituitary hormones, especially for thyrotropin (TSH), in conjunction with other known mechanisms such as Pou1f1-regulated hormone expression. RA signaling also regulates pituitary morphogenesis, likely together with other converging pathways regulating proper pituitary morphogenesis.