This affinity purified antibody has been tested for use in ELISA and western blotting. Specific conditions for reactivity should be optimized by the end user. Although the predicted molecular weight of FIP3 is 82.4 kDa, a band corresponding to FIP3 was observed at 120 kDa in human cell lysates and at 150 kDa in mouse cell lysates. The identity of a 40 kDa band, observed in western blotting against both HeLa and 293T cell lysates, is unknown (personal communication, P. Randazzo, CCR-NCI, Bethesda, MD).