Differential expression of STAT3 and pSTAT3 in various histopathological grades of the HPV16 positive lesions during cervical carcinogenesis. (A) Representative immunoblots showing expression pattern of STAT3 and pSTAT3 proteins in well differentiated (WDSCC), moderately differentiated (MDSCC) and poorly differentiated (PDSCC) squamous cell carcinoma nuclear proteins with densitometric ratio of pSTAT3: STAT3 expression. (B) Representative photomicrographs showing differential expression and nuclear localization of STAT3 on paraffin embedded sections of HPV16+ invasive cervical cancer tissues in various histopathological grades. C. Cumulative data of immunohistochemical evaluation of degree of STAT3 over-expression and nuclear localization which increases as a function of severity of the disease. 1Values indicate percentage of specimens showing either medium or strong overall STAT3 expression on an arbitrary staining intensity grading as described in Methods. 2Percent number of cells showing nuclear positivity in specimen expressing medium or strong STAT3 expression. p value < 0.001 versus values for WDSCCa or MDSCCb as determined by Fischer's Exact Test/Chi Square test. p value < 0.001 versus values for WDSCCc or MDSCCd as determined by t-test.