Although, following 1 mg/kg PD 0325901, concentrations were below the limit of detection in the tumour (<0.4 nmoles/g), this dose was able to reduce (1 hour) and completely ablate (3 and 6 hours) the phosphorylation of ERK1/2, with very little recovery by 24 hours. This evidence concerns the gene MAPK3 and neoplasm.