Selumetinib (AZD6244, ARRY-142886) is a potent, selective, orally bioavailable allosteric MEK1/2 inhibitor (IC₅₀ = 14 nM for MEK1, 10 nM for MEK2). It is widely used as a research tool in biochemical, cellular, and animal models to study the MAPK/ERK signaling pathway, which regulates cell proliferation, differentiation, and survival. Selumetinib locks MEK1/2 in an inactive conformation, preventing ERK phosphorylation and downstream signaling. It is particularly valuable for investigating pathway dysregulation in cancers like neurofibromatosis type 1 (NF1)-associated plexiform neurofibromas, melanoma, non-small cell lung cancer (NSCLC), and thyroid cancer. Clinically approved for unresectable plexiform neurofibromas in pediatric NF1 patients. This high-purity product (≥98.5%) is intended strictly for laboratory research use only and not for diagnostic or therapeutic applications in humans.