Immunofluorescence microscopy analysis of the intracellular location of the MNK/III.6 protein in transfected cells. Me32a cells expressing WtMNK or MNK/III.6 protein were either untreated (A, B), treated for two hours in media containing 5 μmol/l brefeldin A (C, D), or treated for two hours with 200 μmol/l copper (E, F). Cells were probed with affinity purified MNK antibodies (1:1500) followed by a fluorescent Alexa 594 labelled secondary antibody (1:1000), and viewed using 60 × oil objective. Note the perinuclear location of the MNK/III.6 protein in untreated cells and the contraction of this signal in brefeldin A treated cells, similar to the WtMNK protein. The copper induced trafficking of the WtMNK protein is not apparent for the MNK/III.6 protein.