The Alexa Fluor 488 F(ab')2 fragment of rabbit anti—mouse IgG is labeled with our bright, photostable, green-fluorescent Alexa Fluor 488 dye (which is spectrally similar to fluorescein) and is prepared from antibodies that have been adsorbed against human serum to minimize crossreactivity. Conjugates of F(ab')2 fragments are sometimes preferable to whole antibody conjugates for secondary detection, since the absence of the Fc region in F(ab')2 fragments prevents interactions with Fc receptor—bearing membranes. Please note that the rabbit Fc region will bind nonspecifically to human tissue.