Advanced Targeting Systems (ATS) is a San Diego-based biotechnology company dedicated to providing quality targeting reagents for scientific research and pharmaceutical development. Advanced Targeting Systems pioneered the use of targeted toxins. These products include specific lesioning agents for cholinergic basal forebrain neurons, noradrenergic and adrenergic neurons, macrophages and microglia and a pan-neuronal agent that strikes an epitope expressed on all neurons. In addition, ATS produces and sells "second immunotoxins" (or "secondary conjugates") which allow users to convert their own targeting agents into specific cytotoxic tools.