Whereas Rac1 protein level was not significantly related to proliferation, highly proliferative tumours (i.e. >20% MIB-1 positive cells) showed a significant increase in the level of RhoA-like proteins as compared to tumours with low proliferation index (i.e. MIB-1 <5%) (P<0.05). This evidence concerns the gene RAC1 and neoplasm.