MMP1 and neoplasm: MMPs lacking a transmembrane domain are expressed on the surface of other cells including MMP‐1 on keratinocytes (Dumin et al., 2001), MMP‐2 on the surface of endothelial cells, fibroblasts, and tumor cells (Brooks et al., 1996; Itoh et al., 2001; Will et al., 1996), and MMP‐8 and MMP‐9 on the surface of PMNs (Owen et al., 2003, 2004).