Phospholipase C isozymes(PLCs) paly a central role in ligand-mediated signal transduction for cellular activity such as proliferation and differentiation. However, the biolog-ical significance of their molecules in carcinogenesis or tumor progression is not determined precisely yet.

Usnig PLC-γ1 specific antibody, we have examined the relative contents of PLC-γ1 in various types of human cancer tissue, by immunoblotting and imm-unohistochemistry techniques. Several oncogene studies and DNA ploidy sutdy were per-formed additionally insome tumors.

Most malignancy showed elevated contentesof PLC-γ1, especially in colorectal and breast cancer, whereas hepatocellular carcinoma revealed decreased expression pf PLC-γ1. onco-protein expression was correlated with PLC-γ1 expression in some tumors. In hepatocellular carcinoma, DNA ploidy has an influenc to PLC-γ1 expression in most of the cases.

In conclusion, alteration or imbalance of the PLC-γ1 mediated signal trans-duction may have a significant role in the devlelopment or progression of cancer. These findings not only have important implications for increasing our understanding of multistage car-cinogenesis but they also have an impact on strategies for diagnosis and theraly of cancers.