NEDD9, a focal adhesion scaffolding protein, has been recently proposed to 
regulate invasion and metastasis in some cancer types, but unknown in cervical 
cancer. The aim of this study was to determine if NEDD9 was involved in the 
progression and metastasis of cervical cancer. The experimental results showed 
NEDD9 protein was overexpressed in cervical cancer compared with normal cervical 
epithelium tissues. Overexpression of NEDD9 was correlated with histological 
grading, lymph node metastasis, and FIGO stage of cervical cancer. Silencing 
NEDD9 resulted in tyrosine dephosphorylation of FAK and SRC oncoproteins, and 
decreased cell migration and invasion in the cervical carcinoma SiHa and HeLa 
cells. Overexpression of NEDD9 led to tyrosine phosphorylation of FAK and SRC 
oncoproteins, and increased cell migration and invasion. Moreover, tyrosine 
phosphorylation of NEDD9 was significantly decreased via suppressing tyrosine 
phosphorylation of FAK or SRC, suggesting a positive feedback loop of tyrosine 
phosphorylation between NEDD9 and FAK or SRC. In addition, our data showed that 
silencing NEDD9 decreased Vimentin expression and increased E-cadherin 
expression in cervical cancer cells, and vice versa. E-cadherin was subject to 
regulation of NEDD9, FAK and SRC, but altered neither tyrosine-phosphorylated 
nor total NEDD9. Our findings suggest that NEDD9 is overexpressed in cervical 
cancer tissues and cells, and overexpressed NEDD9 promotes migration and 
invasion in cervical carcinoma cells, probably via a positive feedback loop of 
tyrosine phosphorylation between NEDD9 and FAK or SRC.