DMPK and myotonic dystrophy type 1: Even greater reduction in DMPK mRNA was documented in vorinostat-treated control myoblast cultures (Figure S4), as compared with the DM1 cell line; it may be that the documented increased half-life of DM1 expanded DMPK mRNA [17] blunts the normally brisk vorinostat-mediated downregulation of DMPK mRNA levels.