tokens: The primary antibodies used were anti - p53 monoclonal antibody ( clone DO - 7 , 1 / 1000 , DAKO ) , anti - p21 / WAF1 monoclonal antibody ( Ab - 1 , 1 / 200 , Oncogene Research ) and anti - beta - actin monoclonal antibody ( 1 / 1000 ; Chemicon ) as internal control .