The salt eluates were examined for the presence of both DNA replication proteins ( Pol alpha , delta , straightepsilon , PCNA , RFC , RFA , DNA ligase 1 , NDH 2 , Topo 1 and Topo 2 ) and cell cycle proteins ( Cyclins A , B 1 , D 1 , D 2 , D 3 , E , CDK 2 , CDK 4 , CDK 5 and p 21 ) by western blotting with specific antibodies . ^^^