Objective      To verify the different roles of adaptor proteins Crk and Crk-like (CrkL) in the proliferation in ovarian cancer cell line MCAS.       Methods      Co-immunoprecipitation was performed to detect Crk and CrkL endogenous binding proteins that were known to be associated with tumor malignant proliferation in ovarian cancer cell line MCAS. Inducible siRNA was employed to knock down endogenous Crk and CrkL expression in MCAS cells

respectively

and the growth and viability of the inducible Crk/CrkL-knockdown MCAS cells (MACS-Crki/CrkLi) were observed.       Results      Crk rather than CrkL strongly bound to p130Cas and Sos

which were reported to be related with cell proliferation

despite CrkL and Crk had partially the same immunogenicity. The result of Western blotting showed that Crk/CrkL started to be silenced and their expression significantly decreased when exposed to doxycycline (Dox) in MACS-Crki/CrkLi cells (Dox+: Crk 0.021±0.001

CrkL 0.676±0.005; Dox-: Crk 0.544±0.003

CrkL 1.282±0.007; P0.05). Serial observation of the MACS-Crki/CrkLi cells demonstrated that the Dox-induced CrkL knockdown cells presented with gradual detachment from plastic dish and even death

as compared with the Dox-induced Crk knockdown cells with reduced cell growth but remaining viability.       Conclusion      As compared with the role of Crk in malignant proliferation of MCAS cells

CrkL may be involved in some basic biological events associated with MCAS cell survival.