CTSK and infection: Further analysis showed that the ECM-related genes that were upregulated after CA09 infections mainly included metalloenzymes, such as Mmp9 (a member of the matrix metalloproteinases), Adamts15 (proteases containing a prometallo protease domain), Calca (functions as a vasodilator), Ctsk (a member of the peptidase C1 protein family), and other genes that impair the cellular junction and morphology of cells.