Photodamage to proteins of MCF-7c3 cells by Pc 4-PDT. Exponentially growing cultures of MCF-7c3 cells were incubated with nothing (labeled C) or 200 nM Pc 4 for 18 h, then irradiated with 200 mJ/cm2 red light, as described in Methods. Immediately after PDT, cells were collected from the monolayer by scraping and processed for western blot analysis, using antibodies to SERCA2, IP3-R2, IP3-R3, Bcl-2 and actin.