The Alexa Fluor 633 rabbit anti—mouse IgG is labeled with our bright, photostable, Alexa Fluor 633 dye and is prepared from affinity-purified antibodies that react with IgG heavy chains and all classes of immunoglobulin light chains from mouse. To minimize crossreactivity, it has been adsorbed against human serum prior to conjugation. Fluorescence of this long-wavelength Alexa Fluor dye is not visible to the human eye but is readily detected by most imaging systems.