MMP1 and Alzheimer disease: Astrocytes also undergo senescence in response to ROS, and in astrocytes derived from brains of AD patients, there was increased expression of the cell cycle regulator p16, as well as increased matrix metallopeptidase-1 (MMP-1) and IL-6, all of which have also been shown to be upregulated in senescence (Baker and Petersen, 2018).