THE EFFECT OF MOUSE MAMMARY-TUMOR VIRUS RECEPTOR ACTIVATION ON MAMMARY EPITHELIAL-CELL SENSITIVITY TOWARD PROLACTIN

Mammary epithelial cells infected with the mouse mammary tumor virus (MMTV) require less than one-half the concentration of prolactin to elicit ol-lactalbumin production than uninfected tissue (EC(50) 89 +/- 10 ng/ml vs. 206 ng/ml, respectively) Furthermore, stimulating antibodies to the cellular receptor for MMTV halved the prolactin requirement of MMTV- tissue, while MMTV antibodies that sequestered secreted MMTV increased the prolactin requirement in MMTV+ tissue. These data suggest that the effect of MMTV on mammary epithelial sensitivity toward prolactin is being mediated by its interaction with a cell surface receptor. (C) 1994 Academic Press, Inc.