A MEK1 and MEK2 inhibitor (IC50s = 1.8 and 0.92 nM, respectively); selective for MEK1/2 over RAF/MEK/ERK pathway kinases at 10 µM; reduces cell growth in HT-29, COLO 205, and LoVo cells (IC50s = 0.48, 0.52, and 2.2 nM, respectively); reduces tumor volume in a COLO 205 mouse xenograft model at 0.3 mg/kg