States of developmental commitment are encoded as combinations of transcrip
tion factors and changes in their expression can bring about transdifferent
iation or metaplasia. For example, ectopic expressions of Vestigial can con
vert Drosophila leg to wing; of C/EBP beta can convert pancreatic exocrine
cells to hepatocytes; and expression of C/EBP alpha and PPAR gamma can conv
ert myoblasts to adipocytes.