NOTE: PODS® Empty crystals are composed solely of polyhedrin protein. As these PODS® do not contain any cargo protein, they are sold by weight of the polyhedrin protein, rather than cargo weight. This product is intended to be used as a negative control alongside cargo-containing PODS® co-crystals. The cross-reactivity of PODS® Empty crystals has been tested on a variety of cells including mouse ES cells, PC12, fibroblasts, and ETS embryos, and there was no observable interference with the tested cells. Additionally, in-vivo data indicate no inflammatory response to PODS® Empty crystals in animals.