MMP3 and cancer: This study shows that KCNQ1OT1 knockdown induced several cellular senescence markers, including induction of SA-β-gal activity, activation of the p53-p21Cip1/WAF1 pathway, increased H3K9 trimethylation required for SAHF formation, and SASP factor (IL-1β, IL-6, and MMP3) expression, in human cancer HCT116 and MCF-7 cells (Figure 1 and Figure 2A).