All the DLBCL cell lines, irrespectively of their GC or ABC origin, and the BL cell line RAMOS showed some activation of the DDR pathway, as defined by constitutive phosphorylation of CHK1 at ser 345 and/or phosphorylation of CHK2 at thr 68, and constitutive expression of γH2AX, evaluated by Western blot analysis. This evidence concerns the gene CHEK1 and diffuse large B-cell lymphoma.