We also examined the DNA methylation status in the promoter regions of the ABCB1 gene in 27 canine B-cell lymphoma patients [63], but the CpG island of this gene was hypomethylated in most dogs in both the chemotherapy-sensitive and -resistant patient groups, which meant that the DNA methylation status might not change during treatment in dogs with B-cell lymphoma. The gene discussed is ABCB1; the disease is B-cell non-Hodgkin lymphoma.