shRNA knockdown of H3K27 demethylases reduces senescence-associated biomarkers. (A) Representative fluorescence microscopy images of MRC5 cell lines grown in SCM and expressing shRNAs targeting Jmjd3 and Utx. The addition of doxycycline (Dox) at 2 µg/mL activated each shRNA, as indicated by turbo red fluorescent protein (tRFP) reporter expression. Representative images show SA-β-gal staining at 48 h. (B) Quantification for SA-β-gal staining shown in A. (C) RT-qPCR analysis for the expression levels of H3K27 demethylases and SASP genes in control, Jmjd3, and Utx shRNA cell lines at 72 h. (B,C) Student’s t-test; bars represent standard deviation and asterisks indicate statistical significance (n.s., not significant; *, p ≤ 0.05; **, p ≤ 0.01; ***, p ≤ 0.001; n = 3).