A rapid microwell fluorescence immunoassay for cellular protein detection

In this paper, we describe a simple, rapid, specific, sensitive, and reliable method, the FICP method (Fluorescence Immunoassay for Cellular Protein detection) which is readily applicable to the detection of proteins directly on cells cultured in 96-well plates. In order to illustrate this method, we report on the detection of two different proteins, the cell cycle proteins cyclin D1 and p21(CIP1/WAF1), in untreated and 2-cyclopenten-1-one treated breast cancer cells. When the FICP method was compared with Western blot procedure, FICP was found to be superior for many characteristics. By using this method, we were able to quantify biological effects of a specific compound on protein levels in non-lysed cells and perform statistical analysis. Therefore, we believe this screening assay could be very useful for detecting poorly expressed proteins and for drug development.