RG13022 suppresses EGF-stimulated cancer cell proliferation. In a cell-free reaction RG13022 inhibits the autophosphorylation reaction of the EGF receptor in immunoprecipitates with an IC ₅₀ of 4 μM. RG13022 inhibits colony formation and DNA synthesis by HER 14 cells, which were stimulated by 50 ng/mL EGF, in a dose-dependent manner. The IC ₅₀ s are 1 and 3 μM for HER 14 colony formation and DNA synthesis, respectively. RG-13022 inhibits not only EGF-induced growth but also growth stimulated by insulin, insulin-like growth factor I, insulin-like growth factor II, or transforming growth factor alpha. RG-13022 also totally blocks estrogen-stimulated phosphorylation of the EGF receptor, as well as estrogen-induced cell proliferation, suggesting that functioning TK pathways are required for estrogen action.

RG13022 suppresses tumor growth in nude mice. RG13022 also increases the life span of these tumor-bearing nude mice.