MEF2B and diffuse large B-cell lymphoma: C3 (13% of all DLBCL) includes GCB-DLBCL with lesions affecting chromatin regulation (EZH2 mutations, KMT2D mutations, CREBBP or EP300 mutations or deletions), PI3K/AKT signaling (PTEN deletions or mutations, mTOR mutations, MIR17HG amplifications), apoptosis (BCL2 chromosomal translocations), cell motility (GNA13 mutations), and germinal center program (MEF2B or IRF8 mutations).