Tyrosinase activation by the MNK/III.6 protein. Me32a cells co-transfected with the tyrosinase expression plasmid, pcTYR, and either the vector alone (lane 1), or the MNK expression plasmids for WtMNK (lane 2), MNK/III.6 (lane 3), MNK-D1044E (lane 4), or MNK-C1000R (lane 5). The upper panel shows the bands produced by the oxidation of L-DOPA by tyrosinase in transfected cells. The middle panel is an immunoblot showing the corresponding levels of each MNK mutant protein in the transfected cells detected using affinity purified MNK antibodies. The lower panel is an immunoblot showing the corresponding levels of tyrosinase protein in each sample.