For instance, Mcl-1 has been shown to inhibit cell-cycle progression via binding of proliferating cell nuclear antigen (PCNA)8 and Cyclin depending kinase 1 (CDK1).9 In addition, it has been implicated in DNA damage repair,10 what further enhances the probability of Mcl-1 having a tumor suppressor role besides its cell death-preventing function. Here, PCNA is linked to neoplasm.