RHO and neoplasm: Clark et al (2000) have shown that the small GTPase RhoC enhances metastasis when overexpressed, whereas a dominant-negative Rho inhibits metastasis. Analysis of the phenotype of cells expressing dominant-negative Rho or RhoC indicates that RhoC is important in tumour cell invasion. The process of selecting highly metastatic cell lines, as done by Clark et al (2000), resulted in a large number of genes related solely to metastasis, but not to the microenvironmental changes in the preferred target organs.