This means that they share different cellular origins and substrate specificity despite having a common gene [43] It has also been argued that the collagenase species of MMP-8 and/or inductive collagenase-2 are the major ones found in active sites of periodontitis rather than MMP-1, which is demonstrated constitutively as a typical example of a fibroblast-type [44]. The gene discussed is MMP8; the disease is periodontitis.