Ubiquitin is a small (8.5 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e. it occurs ubiquitously. (Wikipedia)(See all definitions)
Alternate reading frame protein (ARF) complexes with mouse double minute 2 homolog 2 (MDM2), an E3 ubiquitin ligase that regulates the stability of p53 and therefore suppressing tumor growth, it is also involved in the immune response, by modulating the tumor environment [46]. (jbiomed.com)
Four of the CNVs were in genes that belong to the ubiquitin gene family, which helps control nerve connections. (sciencemag.org)
«Skeletal muscle from animals randomized to PMI 5011 was demonstrated to have decreased 20S proteasome activity and reduced gene expression of specific proteins as part of the ubiquitin — proteasome system in skeletal muscle», they write. (ergo-log.com)