Lenalidomide hemihydrate (CC-5013 hemihydrate) is a potent inhibitor of TNF-alpha with a IC50 of 13 nM. It induces tyrosine phosphorylation of CD28 on T cells, which subsequently activates NF-κB. It acts as a ligand for the ubiquitin E3 ligase cereblon (CRBN), leading to the selective ubiquitination and degradation of the lymphoid transcription factors IKZF1 and IKZF3 through the CRBN-CRL4 ubiquitin ligase complex.