Pyrazolylpyrrole ERK Inhibitor is a potent, ATP-competitive inhibitor of ERK2 (Ki = 2 nM). This compound is highly selective for ERK2 compared to other kinases such as PKA (Ki = 0.39 M) and JNK3 (Ki = 4 M). Inhibits proliferation of Colo205 cells with an IC50 value of 0.54 M.