Dow AgroSciences have developed cotton (<i>Gossypium hirsutum</i>) line 3006-210-23 through a specific genetic modification of the Acala cotton line GC510 (B690) to be resistant to lepidopteran insects. This novel variety produces a version of the insecticidal protein, Cry1Ac, derived from <i>Bacillus thuringiensis</i>subspr. <i>kurstaki</i>. Delta-endotoxins, such as Cry1Ac protein, act by selectively binding to specific receptors localized on the brush border midgut epithelium of susceptible insect species. Following binding, cation-specific pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry1Ac is lethal only when eaten by the larvae of lepidopteran insects, and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for the d-endotoxins of <i>B. thuringiensis</i> on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.