The 3′UTR in the KDM6B mRNA can control the cellular activity of the produced KDM6B/JMJD3 protein, but the mechanism is unclear. To examine whether 3′UTR-dependent JMJD3 protein complexes are responsible for the observed 3′UTR-dependent protein activity, KDM6B cDNA expression constructs with or without the KDM6B 3′UTR were transfected into HeLa cells grown in SILAC media, followed by co-IP of the HA-tagged JMJD3 protein. Cells were grown in SILAC medium for 5 passages and were validated for amino acid incorporation before the experiment. We did not detect major differences in JMJD3 protein interactors, when JMJD3 was translated from mRNA templates with or without its 3′UTR.