CHEK2 and lymphoma: Components of the DDR pathway CHK1, CHK2 and CDC25c resulted to be expressed in 100% of B cell neoplasms and normal reactive follicles tested (Table 1) but only aggressive lymphomas (BLs and DLBCLs) showed a significant activation of DDR pathway, as demonstrated by the expression of CHK1, phosphorylated at ser 345, and CDC25c, phosphorylated at ser 216 (Table 1).