To determine whether YC-1 plays a role in progestin-stimulated secretion of VEGF from human breast cancer cells, T47-D cells were incubated for 30 min with 10- or 100 μM YC-1 or 1 μM anti-progestin RU-486 [anti-progestin (21–23)]. Here, RBMS1 is linked to breast cancer.