In the last years a series of novel pyrazolopyrimidine derivatives synthesized in our laboratory have been found to be able to inhibit Src phosphorylation and to exert a potent antiproliferative action on different human carcinoma cells, including A431 (epidermoid) and 8701-BC (breast cancer) cell lines overexpressing Src. The gene discussed is SRC; the disease is breast carcinoma.