Many researchers employed mammalian expression system to artificially express can-nabinoid receptors, but immunoblot data that directly prove efficient protein expression can hardly be seen in related research reports. In present study, we demonstrated cannabinoid receptor protein was not able to be properly expressed with routine mammalian expression system. This inefficient ex-pression was rescued by endowing an exogenous signal peptide ahead of cannabinoid receptor pep-tide. In addition, the artificially synthesized cannabinoid receptor was found to aggregate under rou-tine sample denaturing temperatures (i.e., ≥95°C), forming a large molecular weight band when analyzed by immuno-blotting. Only denaturing temperatures ≤75°C yielded a clear band at the pre-dicted molecular weight. Collectively, we showed that efficient mammalian expression of cannabi-noid receptors need a signal peptide sequence, and described the requirement for a low sample dena-turing temperature in immuno-blot analysis. These findings provide very useful information for effi-cient mammalian expression and immuno-blotting of membrane receptors. Many studied employing mammalian expression system to artificially express can-nabinoid receptors, but immunoblot data that directly prove efficient protein expression can hardly be seen in related research reports. In present study, we demonstrated cannabinoid receptor protein was not able to be properly expressed with routine mammalian expression system. This inefficient ex-pression was rescued by endowing an exogenous signal peptide ahead of cannabinoid receptor pep-tide. In addition, the artificially synthesized cannabinoid receptor was found to aggregate under rou-tine sample denaturing temperatures (ie, ≧ 95 ° C), forming a large molecular weight band when analyzed by immuno-blotting. Only denaturing temperatures <75 ° C yielded a clear band at the pre-dicted molecular weight. Collectively, we showed that efficient mammalian expression of cannabi-noid receptors need a signal peptide sequence, and described the requirement for a low sample dena-turing temperature in immuno-b lot analysis. These findings provide very useful information for effi-cient mammalian expression and immuno-blotting of membrane receptors.