CXCR2 and breast cancer: Less than 1% of nerve resident immune cells express markers for granulocytes (GC, Cxcr2/C-X-C motif chemokine receptor 2), monocytes (Mo, Chil3/chitinase-like protein 3), or B cells (BC, Cd79a/B cell antigen receptor-associated protein), indicating these cell types are sparse in the naïve PNS of healthy mice.