Similarly, the non-constitutive, furin-independent processing of proMMP14 was also reported to occur in fibrosarcoma HT-1080 and CCL-137 normal fibroblast cells, where the 63 kDa proform of MMP14 was detected in both, the tumor-derived cell line and in normal cells upon PMA stimulation [39,40]. This evidence concerns the gene MMP14 and fibrosarcoma.