Presence of HPV 16 E6 and E7 has different effect on SFK protein and mRNA expression in proliferating human keratinocytes. (A) Western blot analysis of human foreskin keratinocytes (HFK) transduced with HPV 16 E6, E7 or both oncogenes. Levels of cellular p53 and Rb proteins are reduced in the presence of functionally active HPV 16 E6 and E7 oncoproteins, respectively. (B) Analysis of Src, Yes, and Fyn protein expression by western blot using antibodies specific for the native form of the kinases and for a C-terminal tyrosine residue that is phosphorylated upon activation. Actin was used as loading control. The results shown are representative of three independent experiments. (C) The effect of HPV 16 oncogenes on the relative mRNA expression of ubiquitously expressed SFKs in HFK cells. Real-time PCR analysis of Src, Yes, and Fyn was performed using RNA purified from HPV 16 E6 and/or E7 transduced HFK cells. The values were normalized against GAPDH mRNA and presented as relative levels with respect to the value of cells transduced by LXSN. The bars represent the mean ± SEM of two independent experiments, each with triplicate measurements. Two-tailed Student t test revealed no significant, HPV related alteration in any of the tested SFK mRNA levels.