 Fibroblast growth factor

A fibroblast growth factor is a member of a signalling-protein family whose receptor interactions regulate processes including cell proliferation, survival and cell differentiation. Many members act through FGF receptors, a class of receptor tyrosine kinases. The historical family name does not limit their targets to fibroblasts. ^[ref]

FGF8 provides a developmental example: localized production, receptor distribution and surrounding regulatory interactions help determine where cells respond. A signal's spatial effect depends on more than its concentration at the source. Detecting FGF expression therefore identifies a potential signalling input, while receptor activation and a subsequent change in cell fate require separate evidence.