Some fluctuations in the expression of GPIIb/IIIa on the ADP-stimulated platelets were identified in the course of five-week breast cancer development, one of which being the increase of activated GPIIb/IIIa complex expression, the receptor for fibrinogen, immediately after 4T1 cell injection, which then fell five weeks later. The gene discussed is ITGA2B; the disease is breast carcinoma.