['Intimal thickening is considered to result from the dedifferentiation of medial smooth muscle cells (SMCs) from a contractile to a synthetic phenotype, and their subsequent migration and proliferation. It is unknown whether nectin-like molecule (Necl)-5, which is overexpressed in cancer cells, is involved in intimal thickening.', 'Necl-5 was upregulated in mouse carotid artery after ligation. Compared with wild-type mice, intimal thickening after carotid artery ligation was milder in Necl-5 knockout mice. In vitro, the expression levels of SMC differentiation markers were higher, whereas the expression level of an SMC dedifferentiation marker was lower, in Necl-5 knockout mouse aortic SMCs (MASMCs) compared with wild-type MASMCs. The migration, proliferation, and extracellular signal-regulated kinase activity in response to serum were decreased in Necl-5 knockout MASMCs compared with wild-type MASMCs. In wild-type MASMCs, inhibition of extracellular signal-regulated kinase activity increased the expression levels of SMC differentiation markers and decreased their migration and proliferation in response to serum.'] Does nectin-like molecule-5 regulate intimal thickening after carotid artery ligation in mice?