C12FDGlcU is a lipophilic analog of fluorescein di-β-D-glucuronic acid. C12FDGlcU can be useful for the detection of β-glucuronidase (GUS) gene expression. C12FDGlcU can enter the cells and then be cleaved by β-glucuronidase , generating the yellow-colored, green-fluorescent fluorescein (Abs/Em of the reaction product: 495/518 nm).