PCNA and acute lymphoblastic leukemia: Silencing of exosomal miR-181a reverses childhood ALL cell proliferation in vitro by upregulating proliferative (PCNA-encoding proliferating cell nuclear antigen and MKI67-encoding marker of proliferation Ki-67) and pro-survival genes (MCL1 apoptosis regulator and BCL2) and by suppressing proapoptotic genes (BAD of BCL2-associated agonist of cell death and BAX of BCL2-associated X apoptosis regulator) [197].