CXCR1 and MALT lymphoma: In comparing gastric to extragastric MALT lymphomas, the upregulation of CXCR1 and CXCR2 accompanied by downregulation of CCR8 and CX3CR1 and loss of XCR1 expression in extragastric MALT lymphomas appear to be key determinants for the site of origin of MALT lymphomagenesis [45].