sentences:  Cyclin D/Cdk4
  
  The Cyclin D/Cdk4 complex is a multi-protein structure consisting of the proteins Cyclin D and cyclin-dependent kinase 4, or Cdk4, a serine-threonine kinase.This complex is one of many cyclin/cyclin-dependent kinase complexes that are the "hearts of the cell-cycle control system"  and govern the cell cycle and its progression.