DUSP6 and neoplasm: Finally, in a survey of either drug naïve (n = 15) or drug resistant (n = 10) ELM4–ALK patient tumours DUSP6/MKP-3 protein levels as detected and scored by immunohistochemical staining were significantly lower in the drug resistant samples, while in 5 out of 6 (80%) of paired tumour biopsies from patients taken either before or after drug treatment DUSP6 expression was lower in the resistant samples.