MMP1 and myotonic dystrophy type 1: We evaluated MMP1 and MMP3 expression in the DM1 model cells at days 51 and 63 by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and found that the expression of these genes was significantly increased in CUGexp+ cells (p = 0.0087 and 0.023 at day 51, and p = 0.0002 and 0.0007 at day 63, respectively, Figure 3A), suggesting that CUGexp RNA alters the expression of several ECM-degrading enzymes related to cellular senescence.