The findings that CLL patients with more aggressive disease are characterized by higher CAT levels [19] and ERK1/2 activation [19, 49], together with data on the function of rs1001179 T as a binding sequence for ETS1, could be suggestive of a possible role of the ERK1/2-ETS1 pathway in the transcriptional regulation of CAT that deserves to be further investigated. Here, MAPK3 is linked to B-cell chronic lymphocytic leukemia.