Functional analysis of cyclin D2 and p27Kip1 in cyclin D2 transgenic mouse mammary gland during development

Abstract
Two mammary gland phenotypes were detected in pregnant MMTV-cyclin D2 transgenic mice; line D2–53 exhibited a lack of alveologenesis and failure to nurse, whereas line D2–58 featured a reduction in alveologenesis, but retained normal nursing behavior. In pregnant mammary glands, cyclin D2 protein levels were twofold (PPkip1 protein level oscillated in a similar profile in wild type and cyclin D2 transgenic mice, but was consistently higher in the cyclin D2 mice suggesting that p27kip1 functions downstream of cyclin D2. The ratio of p27kip1-cdk4/p27kip1-cdk2 was 6.5-fold (PPkip1 protein level and inhibition of cyclin D1 phosphorylation.