A transforming growth factor related to epidermal growth factor is expressed by fetal mouse salivary mesenchyme cells in culture.

Fetal mouse salivary mesenchyme cells secrete a protein with an apparent MW of 15 Kd that is immunologically related to epidermal growth factor (EGF). Conditioned medium collected from these cells in culture stimulates the growth of primary mouse mammary epithelial cells cultured within collagen gels, competes for binding to EGF receptor sites on these mammary epithelial cells and stimulates the anchorage-independent growth of normal rat kidney fibroblast cells within soft agarose. Prior immunoprecipitation of salivary mesenchyme cell conditioned medium with anti-EGF antibodies effectively removes or attenuates all of these effects confirming that an EGF-like factor is involved in these responses.