In the B-cell-deficient mouse model of Kras-expressing pancreatic intraepithelial neoplasia (PanIN), adoptive transfer of CD5+CD1dhi Breg cells rescued the tumor growth deficiency (69); Meanwhile, a study using a mouse model of melanoma showed that Breg cells with B220+CD23+IgMhiCD21hi T2-MZP phenotype specifically accumulated in tumor-draining lymph nodes (LNs) and promoted tumor growth in an IL-10-independent manner (25, 74). Here, KRAS is linked to neoplasm.