PCNA and neoplasm: Other NCR-Ls are represented by nuclear antigens that can reach the plasma membrane during tumor transformation and can be expressed in exosomes by tumor cells: Proliferating cell nuclear antigen (PCNA), recognized by NKp44, and HLA-B-associated transcript 3 (BAT3), also known as BCL2-associated athanogene 6 (BAG6), by NKp30 [49,50].