Recent gene expression profiling studies of 26 HCL patients confirmed DUSP6 as a transcriptional target of the constitutively activated BRAF-MEK-ERK pathway [18].Interestingly, DUSP6 is also regulated upon extracellular growth factor stimulation and serves as an essential mediator of fibroblast growth factor (FGF) dependent ERK activation in prenatal development [40]. Here, DUSP6 is linked to hairy cell leukemia.