CCL21 and neoplasm: Although Eμ-Myc tumor cells expressed higher levels of the collagen-degrading matrix metallopeptidase (Mmp)-14 than benign B cells, while FRCs upregulated Mmp9 (Figure S7B), the application of broad spectrum MMP inhibitors did not impede the tumor-induced remodeling, as determined by the frequencies of PNAd+ BECs and CCL21+ FRCs in tumor-exposed LNs (Figure S7C).