miR-125b regulates apoptosis in mature hematopoietic cells by blocking the pro-apoptotic Bak1 protein, is also responsible for the resistance to chemotherapeutic agents used to treat leukemia, such as vincristine and daunorubicin, and plays a significant role in the regulation of p53 protein expression and influences the activity of the NF-κB factor [22,23,24]. The gene discussed is BAK1; the disease is leukemia.