Gender Differences in Susceptibility to Environmental Factors: A Priority Assessment - Workshop Report cellular level. In addition, there is much to be learned from animal models, not only from the knockout mice (as described in the workshop summary) but ... from gene insertion and substitution techniques (e.g., so-called "knock in" mice and "hit and run" experiments). At the same time, however, new techniques are needed to validate animal models of human disorders; assistance in translating those validation techniques into simple tests that can be used in the field are equally necessary. For these reasons, basic researchers should look for the broader implications of the mechanistic research conducted at the molecular, cellular, and animal levels. In particular, sponsoring agencies should encourage the development of animal models that are directly relevant to (1) gender differences in susceptibility and severity and (2) human exposures and diseases. III.