MYC expression and regulation in the formation of the normal GC reaction. MYC is initially expressed in B cells after interaction with antigens and T cells and is essential for GC formation. The subsequent up-regulation of BCL6 represses MYC and initiates the formation of the GC dark zone (DZ). MYC is reexpressed in a subset of cells of the light zone (LZ) after NF-κB up-regulation that will reenter into the DZ for subsequent rounds of IG somatic mutations. MYC-negative cells in the LZ exit the GC as memory cells or early plasmablasts. BLIMP1 induction will promote plasma cell differentiation and repress MYC.