The transforming genes E6 and E7 of high risk human papillomaviruses (HPVs) are consistently expressed in papillomavirus-associated neoplasm of the anogential tract. Although the molecular mechanism by which these oncogenes contribute to the malignant phenotype is not clear, the interaction of the cellular tumor suppressors (p53 and pRB) with the E6 and the E7 proteins correlates with their oncogenic potential. To study the effects of the transforming genes E6 and E7 on the cellular signal transduction processes, we examined the effect of HPV E6 and E7 proteins on the transcription of PLC-γ1 promoter by CAT assay. E6 proteins of HPV-11 and HPV-18 do not repress the transcription of PLC-γ1 promoter and E7 proteins of HPV-11 and HPV-18, in contrast, repress the PLC-γ1 promoter. Particularly E7 proteins of the High-risk group (HPV-18) is able to repress the transcription from PLC-γ1 promoter to some significant extent. These observations suggest that transforming genes E7 of HPVs have ability to down-regulate PLC-γ1 mediated signal transduction pathway.