Figure 5

Effect of heat treatment on the relative expression of ER isoforms. Human breast cancer cytosols were heated at 37°C for 2 min in the presence or absence of protease inhibitors. They were then labelled with [¹²⁵I]TAZ in the presence or absence of a 200-fold excess of radioinert oestradiol, immunoprecipitated with H-222 anti-ER monoclonal antibodies, and then subjected to SDS-PAGE. Lane 1, unheated control; lane 2, plus an excess of oestradiol; lane 3, 2 min heating in the absence of protease inhibitors; lane 4, 2 min heating in the presence of protease inhibitors.