Key decatenating enzyme that alters DNA topology by binding to two double-stranded DNA molecules, generating a double-stranded break in one of the strands, passing the intact strand through the broken strand, and religating the broken strand. Plays a role in B-cell differentiation. {ECO:0000269|PubMed:10684600, ECO:0000269|PubMed:31409799, ECO:0000269|PubMed:32128574}. This is the function of TOP2B (DNA topoisomerase II beta, Ensembl gene identifier ENSG00000077097).