PP2

PP2 is a potent, reversible, ATP-competitive, and selective inhibitor of the Src family of protein tyrosine kinases with IC₅₀s of 4 and 5 nM for Lck and Fyn, respectively. IC50 & Target: IC50: 4 nM (Lck), 5 nM (Fyn)^[1] In Vitro: At 10 μM, the effect of PP2 on cellular proliferation is not significant, indicating that, at this low concentration, the effect of PP2 on Gemcitabine cytotoxicity does not simply reflect a direct antiproliferative effect, but rather a potentiation of Gemcitabine-induced cytotoxicity. Above 20 μM, growth is increasingly suppressed, a finding consistent with reports in other human cancer cell lines. Although 10 μM PP2 is used in our study, at higher concentrations PP2 is reported to inhibit other intracellular kinases^[2]. PP2 is the most widely used commercially available Src family kinase inhibitor. PP2 inhibits Src family kinase activity with IC₅₀ of ~5 nM in vitro, concentrations to 10 μM are often necessary to achieve complete Src family kinase inhibition in cell culture^[3]. In Vivo: The tumor growth inhibition rate is 25% in the PP2 treatment group and 5% in the Gemcitabine treatment group (P>0.05). When administered in combination, PP2 and Gemcitabine produce a tumor growth inhibition rate of 98% (P<0.05). Hepatic metastasis occurred in 100% of control and Gemcitabine-treated groups; 88% of the PP2-treated group developed liver metastases. There are no detectable metastases in the group treated with PP2 and Gemcitabine in combination (P<0.05)^[2].