The Ras-MAP kinase pathway is essential for the differentiation of neuronal cells and myocytes; it is inhibited by Spred1, a member of the Sprouty family of proteins. Spred1 acts by suppressing the phosphorylation and activation of Raf. The Spred proteins have also been implicated in the negative feedback regulation of FGF signaling in embryogenesis and angiogenesis. Further studies have shown that expression levels of Spred1 and Spred2 proteins are inversely correlated with the incidence of tumor invasion and metastasis in human hepatocellular carcinoma (HHC), suggesting that these proteins could be useful as prognostic factors and therapeutic targets in HCC. Defects in this gene are a cause of neurofibromatosis type 1-like syndrome (NFLS).