Autocrine motility factor is a growth factor.

Autocrine motility factor (AMF) is a 55 kDa cytokine which is produced and secreted by cancer cells and which regulates cell motility via binding to its receptor, a 78 kDa cell surface glycoprotein (gp78-AMFR), and activating a pertussis toxin (PT)-sensitive G-protein. AMF purified from HT-1080 human fibrosarcoma cells stimulates the growth and motility of 3T3-A31-fibroblasts at a concentration of 0.1 ng/ml or less. The expression of total as well as cell surface gp78-AMFR is down-regulated in contact-inhibited A31-fibroblasts and AMF stimulates the healing of experimentally wounded, density-arrested A31 monolayer cultures. This is the first report of the paracrine and mitogenic actions of AMF and the results presented here show that AMF functions as a growth factor and suggest a possible role for its activity in normal tissue regeneration and tumor cell dissemination.