Taken together, we have the first time demonstrated C/EBPβ PARylation inhibits C/EBPβ SUMOylation, and SUMO1 is indispensable in PARP1-induced cardiac hypertrophy because of its regulation of C/EBPβ SUMOylation and subsequent C/EBPβ protein stability. Here, SUMO1 is linked to cardiac hypertrophy.