Figure 3.

Key themes from studies of signaling pathways in ES cells. (A) Signaling pathways can directly connect to key transcription factors in the core interconnected autoregulatory loop through terminal components of their signal transduction pathway. (Colored ovals) Proteins; (orange rectangles) genes; (squiggly lines) their resulting transcripts. An arrow from a protein to a gene indicates direct regulation of the gene by the protein. (Red Y shape and long squiggly arrow) Wnt signal transduction pathway. (B) The terminal component of signaling pathways such as the Wnt pathway can form a feedforward loop by regulating both the key regulators and their target genes. Proteins, genes, and regulation are depicted as in A.