Will they work with fixed or paraffin cells?

No, our fluorescent protease detection reagents will not work with fixed cells, nor will they work with paraffin-embedded cells. The reagents' detection mechanisms require the enzymes to be active; fixation and paraffin inactivate the enzymes.  It is possible, however, to fix the cells after labeling and washing.  Our FLICA and FLISP kits include fixative.