Fig. 3
MMP-1 induction in senescent cells after combined exposure to UVA and CSS. ASF-4-1 cells were passaged 1:4 once per week, increasing PDL by 2. Cells above PDL55 exhibit aging phenotype. (A) MMP-1 and COL1A1 mRNA expression 24 h after combined exposure to UVA and CSS. ASF-4-1 cells with PDL42 (normal cells) and 56 (senescent cells) were irradiated with UVA (15 kJ/m2), followed by treatment with CSS (2%). After incubation for 24 h, RT-qPCR was performed. *p < 0.05, **, ##p < 0.01, ***, ###p < 0.001 (vs. untreated). (B) Protein levels of MMP-1 24 h after combined exposure to UVA and CSS. ASF-4-1 cells (PDL42 and PDL58) were irradiated with UVA (15 kJ/m2), followed by treatment with CSS (2%). After incubation for 24 h, cells were lysed and Western blotting was performed. Actin was used as a standard for the equal loading of proteins for SDS–PAGE