Copyright information:Taken from "Fibroblast-derived MT1-MMP promotes tumor progression in vitro and in vivo"BMC Cancer 2006;6():52-52.Published online 6 Mar 2006PMCID:PMC1450297.Copyright © 2006 Zhang et al; licensee BioMed Central Ltd. The human FaDu HNSCC tumor cell line was cultured alone or in combination with WT, MMP-2 null, MMP-9 null, or MT1-MMP null fibroblasts atop type I collagen for 6 days (A, and quantified in B). Experiments were conducted in DMEM with 10% WT, MMP-2 null or MMP-9 null serum. Gelatin zymography of 18-hour serum free conditioned media from FaDu tumor cells in coculture with fibroblasts atop collagen (2:1 ratio) normalized for cell-number.