Our analyses indicate that DLC1 expression is higher than DLC2 and DLC3 in several normal tissues, and that, in tumor types arising in these tissues, it is down-regulated to a degree that is greater than or equal to the down-regulation of DLC2 and DLC3. Furthermore, we have found experimentally that the biological activity of the three DLC proteins may be similar. Here, DLC1 is linked to neoplasm.