Y-27632 dihydrochloride is a potent, cell-permeable, and selective inhibitor of Rho-associated coiled-coil containing protein kinase (ROCK), specifically targeting ROCK1 and ROCK2. It is a white to off-white crystalline powder with the chemical name (R)-(+)-trans-N-(4-Pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide dihydrochloride. This compound is widely recognized as a key research tool in cell biology. Its primary application is as a highly specific small molecule inhibitor in life science research. Y-27632 is extensively used to study the Rho/ROCK signaling pathway, which is involved in diverse cellular processes including actin cytoskeleton organization, cell adhesion, migration, and apoptosis. A landmark application is its use to significantly improve the survival and cloning efficiency of human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells by inhibiting ROCK-mediated apoptosis, a critical technique in stem cell research and regenerative medicine. Beyond basic research, Y-27632 and related ROCK inhibitors have been investigated for potential therapeutic applications in various diseases, such as cardiovascular disorders (e.g., hypertension, cerebral vasospasm), neurological conditions, glaucoma, and cancer, due to their role in regulating smooth muscle contraction, inflammation, and cell motility. It is supplied as a ready-to-use solution or lyophilized powder for in vitro and in vivo studies.