Migration-stimulating factor: a genetically truncated onco-fetal fibronectin isoform expressed by carcinoma and tumor-associated stromal cells.

Migration-stimulating factor (MSF) is a 70-kDa motogenic protein previously reported to be expressed by fetal and cancer patient fibroblasts cultured in vitro and present in the serum of breast cancer patients. A 2.2-kb full-length MSF cDNA has been cloned and shown to be a truncated isoform of fibronectin generated from its primary gene transcript by a hitherto unrecognized intron read-through mechanism.