Cripto/TDGF1 is a member of the epidermal growth factor (EGF)- Cripto, Frl-1, and Cryptic (CFC) family. TDGF1 is an extracellular, membrane-bound signaling protein that plays an essential role in embryonic development and tumor growth. It is overexpressed in many types of cancers and acts as a growth factor for tumors. Cripto mutants display defects in mesoderm induction and heart morphogenesis, similar to phenotypes seen in Nodal mutants. Cripto can also activate mitogen-activated protein kinase (MAPK) and Akt pathways independently of Nodal by directly binding to a membrane-associated heparan sulfate proteoglycan, glypican-1.