HDAC4 and lung adenocarcinoma: We investigated the role of 33 SUMOylation-modified regulatory genes in lung adenocarcinoma, namely, SUMO isoforms (SUMO1, SUMO2, SUMO3, SUMO4), SUMO-Activating Enzyme (SAE1, UBA2), SUMO-Conjugating Enzyme (UBE2I), SUMO E3 Ligases (BCL11A, CAPN3, CBX4, HDAC4, HDAC7, MUL1, NSMCE2, PIAS1, PIAS2, PIAS3, PIAS4, RANBP2, RANGAP1, RNF212, RWDD3, TOPORS, TRIM27, TRIM28, ZMIZ1), SUMO proteases (HINT1, SENP1, SENP2, SENP3, SENP6, SENP5, SENP7, USPL1).