Speake et al. analyzed conditioned medium from a fibrosarcoma cell line (55), and demonstrated pro-MMP-2 and pro-MMP-9 levels to peak at 24 and 48 h post-RT, respectively, whereas others found MMP-2 secreted by lung tumor cells to peak at 12 h (58) or 24 h (57) post-RT. Here, MMP2 is linked to fibrosarcoma.