HIPK2 is SUMOylated at lysine-32 with SUMO1. (Lysine-25 is cited by Hofmann et al. 2005 and Gresko et al. 2005, however the sequence motif listed in Hoffmann et al. 2005 corresponds to lysine-32 of the UniProt reference protein. An alternative isoform having lysine-25 is listed as accession AAG35710 in GenBank.) SUMOylation of HIPK2 disrupts interaction of HIPK2 with GROUCHO corepressor, inhibits JNK activation, and inhibits p53-independent antiproliferative function.