Indeed, we detected a set of metallo-proteinases (MMP2, MMP14), collagens (e.g. COL6A1, COL3A1, COL5A1 and others) and elastin (ELN), which showed a significant longitudinal change in expression in addition to being closely correlated to skin aging (Supplementary Table S3) (41,42). This evidence concerns the gene ELN and skin aging.