DUSP4 and diffuse large B-cell lymphoma: In GCB-DLBCL, positive regulation of the MAPK pathway by CXCR4 expression was suggested by the upregulation of DOK5, PTHLH (which transports calcium), and STIM2 (which activates Ca2+ entry channels) and the downregulation of its negative regulator DUSP4. In contrast, in ABC-DLBCL, negative regulation of MAPK by CXCR4 signaling was indicated by the downregulation of FYN upstream of the MAPK signaling pathway, and the downregulation of calcium-dependent molecules such as MFAP4. In the GCB subtype, CYLD and UBD which activate NF-κB were downregulated in CXCR4+ compared to CXCR4− DLBCL patients.