Additionally, we have observed a significant increase in the DHFR level in acute lymphoblastic leukemia cells (CCRF-CEM) after treatment with CX-4945 (Wińska et al., 2019), which might indicate the possible involvement of CK2 in the regulation of thymidylate synthesis and, therefore, may affect CX-4945 therapy outcome. This evidence concerns the gene DHFR and acute lymphoblastic leukemia.