We previously showed that the formation of protein complexes between MYC and its partner MIZ1 (MYC-interacting zinc finger 1) is critically required for germinal center (GC) B cell expansion (Toboso-Navasa et. al., JEM 2020). MYC and MIZ1 are transcriptional activators; however, they can form a transcriptional repressor complex that represses MIZ1 target genes. High expression of MYC is commonly found in aggressive B cell lymphoma, most notably in Burkitt Lymphoma (BL) and in a fraction of Diffuse B cell lymphomas (DLBCLs). In DLBCL, MYC positivity is associated with poorer prognosis, especially when co-expressed with BCL2, and increased proliferative capacity. However, it remains unclear whether the requirement for MYC-MIZ1 complexes for cell expansion is retained in lymphoma, similar to what we observed in GC B cells.