Sef (similar expression to fgf genes) was identified as a feedback antagonist of FGF signaling in zerbrafish, mouse and human. Sef has been reported to function in different ways, however the regulation of Sef stability remains unknown. The possible role of c-Cbl in the regulation of Sef protein degradation was investigated. Results from coimmunoprecipitation and immunostaining assays reveal that hSef colocalizes and interacts with c-Cbl. Data suggest that the interaction between hSef and c-Cbl results in the ubiquitination and subsequent degradation of the hSef protein. It was proposed that c-Cbl may serve as a modulator to regulate Sef protein stability during FGF signal transduction.