Figure 7.

Model for stage-specific regulation of cartilage development by Notch1 signaling during ESC differentiation. Activation of Notch signaling in ESCs induces the expression of Sox9, which directs differentiation first along the ectodermal lineage and then into neural crest precursors and further in chondrogenic precursors. At the same time, Notch signaling represses differentiation of ESCs into the mesodermal lineage, possibly by the Notch target genes of the Hes/Hey family of transcriptional repressors. Terminal differentiation into chondrocytes and cardiac muscle cells is blocked most likely also by induction of Hes/Hey genes