The estrogen antagonist ICI 182780 does not inhibit the in vitro transformation of MCF-10A cell by E2 and 4-OH-E2.

Anchorage independent growth of 5000 untreated and E2 or 4-OH-E2 (100 ng/ml) treated MCF-10A cells in the presence or absence of an equal concentration of ICI 182780 was monitored by growing these cells for a minimum of 21 days over agar layer. The number of colony formed in each well was determined by a count of the number of colonies >63αum in diameter and data expressed as mean of the number of colonies formed in the four wells +/− S.D.