Relationship between the estrogen induced protein ip and other parameters of estrogenic stimulation. A hypothesis.

Data concerning the estrogen-induced protein “IP” discovered by Notides and Gorski are reviewed. Estrogen specificity of the IP response, physiological occurrence of IP and inducibility of an IP-like protein in target tissues other than the rat uterus are considered. Available information concerning the relative ability of different estrogenic and anti-estrogenic compounds to promote IP synthesis, the uterotrophic responses and the receptor depletion-replenishment cycle is examined. From this the hypothesis is proposed that IP induction may be related with receptor replenishment. Recent data concerning the “receptor cycle” are briefly reviewed in order to envisage further extension of our hypothesis.