To determine whether increased M cell-density in the intestine altered oral prion disease susceptibility, groups of C57BL/6 mice were treated daily with RANKL (or PBS as a control) for 4 d as above, and between the 3rd and 4th treatments (coincident with the peak period of induction of M-cell gene expression in the gut epithelium [22, 35]) the mice were orally exposed to either a moderate (1%) or limiting (0.1%) dose of ME7 scrapie prions. The gene discussed is TNFSF11; the disease is prion disease.