Given our results of a significantly positive association between plasma membrane/perinuclear and cytoplasmic Rac1 expression, abundant cytoplasmic Rac1 expression, as well as its plasma membrane and/or perinuclear immunoreactivity, appeared to be required for an increase in its active form in astrocytomas, in line with increased malignant potential. This evidence concerns the gene RAC1 and astrocytoma (excluding glioblastoma).