biostudies-literatureUnknown23(14)Thumkeo DRho-associated kinase (ROCK), including the ROCK-I and ROCK-II isoforms, is a protein kinase involved in signaling from Rho to actin cytoskeleton. However, in vivo functions of each ROCK isoform remain largely unknown. We generated mice deficient in ROCK-II by gene targeting. ROCK-II(-/-) embryos were found at the expected Mendelian frequency until 13.5 days postcoitum, but approximately 90% died thereafter in utero. ROCK-II(-/-) mice of both genders that survived were born runts, subsequently developed without gross abnormality, and were fertile. Whole-mount staining for a knocked-in lacZ reporter gene revealed that ROCK-II was highly expressed in the labyrinth layer of the placenta. Disruption of architecture and extensive thrombus formation were found in the labyrinth layer of ROCK-II(-Molecular and cellular biology5043-55https://www.ebi.ac.uk/biostudies/studies/S-EPMC162229biostudies-literatureTargeted disruption of the mouse rho-associated kinase 2 gene results in intrauterine growth retardation and fetal death.PMC162229Hirose MNarumiya SKeel JNonomura KThumkeo DOshima MIshizaki TOshima HTaketo MMfalseTargeted disruption of the mouse rho-associated kinase 2 gene results in intrauterine growth retardation and fetal death.Rho-associated kinase (ROCK), including the ROCK-I and ROCK-II isoforms, is a protein kinase involved in signaling from Rho to actin cytoskeleton. However, in vivo functions of each ROCK isoform remain largely unknown. We generated mice deficient in ROCK-II by gene targeting. ROCK-II(-/-) embryos were found at the expected Mendelian frequency until 13.5 days postcoitum, but approximately 90% died thereafter in utero. ROCK-II(-/-) mice of both genders that survived were born runts, subsequently developed without gross abnormality, and were fertile. Whole-mount staining for a knocked-in lacZ reporter gene revealed that ROCK-II was highly expressed in the labyrinth layer of the placenta. Disruption of architecture and extensive thrombus formation were found in the labyrinth layer of ROCK-II(-2003-01-01T00:00:00Z2003 Jul2025-04-19T08:16:13.196Z2020-11-07T10:18:27ZS-EPMC1622291283248810.1128/MCB.23.14.5043-5055.200310.1128/mcb.23.14.5043-5055.2003