COX-2 protein expression in breast and ovarian cancer cell lines stably transfected with E1A. (a) MDA-MB-231-E1A stable transfectants produced the greatest amounts of COX-2; MDA-MB-435-E1A cells produced 78% of that amount, but the SKOV3.ip1-E1A and MCF-7-E1A cells produced only 6% of that amount. MDA-MB-231-E1A cells expressed slightly more E1A than the other three cell lines. (a) COX-2 protein expression level between the E1A stable transfectants and their corresponding vector control cells or parent cells. If the COX-2 expression levels of each E1A transfectant is defined as 100%, the corresponding COX-2 expression levels of the vector controls were as follows: 65% for MDA-MB-231, 144% for MDA-MB-435, 71% for SKOV3.ip1 and 67% for MCF-7.