One study used FVB strain erbB2 (HER2) mutant mice with genetic prepositions to mammary tumors and found that when supplied with Lactobacillus reuteri to the gut, the mouse immune system triggered CD4+CD45RBloCD25+ lymphocyte (Treg cells) protective mechanisms to inhibit cancer progression (47). The gene discussed is ERBB2; the disease is breast cancer.