DUSP6 and cancer: Despite early confusion as to which Ras effector pathway signals to the DUSP6/MKP-3 promoter, with both phosphatidylinositide 3-kinase (PI3K) and ERK signalling implicated in its regulation, it is now clear that DUSP6/MKP-3 is an ERK target gene and that it acts as a classical negative feedback regulator of ERK activity, both in a developmental context and in primary and cancer cell lines [16], [17], [18].