– Transforming growth factor beta (TGFβ) family members are secreted in inactive complexes with a latency-associated peptide (LAP), a protein derived from the N-terminal region of the TGFβ gene product. Extracellular activation of these complexes is a critical step in regulation of TGFβ function in vivo. The TGFβ1 LAP is a ligand for the integrin αvβ6 and that αvβ6-expressing cells induce spatially restricted activition of TGFβ1. And LAP identifies a novel CD4+/CD25+ regulatory T cell subset with TGFbeta-mediated function and enhanced suppression of experimental autoimmune encephalomyelitis.