In the early 1960’s, Dr. Jerry Hirsch demonstrated a genetic basis for behavior using fruit fly lines he selected for an extreme response to gravity (geotaxis). Geotactically positive fruit flies tend to travel in the direction of gravity (Lo), and geotactically negative individuals will travel against gravity (Hi) through a vertical (T-choice) maze. These established Hi and Lo flies have since been used as models for the genetic basis of complex behavior. Toma et al., 2002 found a significant effect of the Pdf protein in the geotaxis behavioral response. Flies unable to make Pdf protein are geotactically high and tend to travel against gravity. We have identified several proteins within the literature that interact with Pdf and have obtained mutant fly lines that are either unable to make or make for than normal amounts of these proteins. These are each being bred into a geotactically neutral laboratory line (Canton-S, CS) to test the effect of these individual proteins on complex behavior. We have successfully bred and run a control group (CS) and 10 different mutant fly lines with only five mutations left to finish breeding and collect maze run data on. Any deviation from CS scores in the maze by these mutant flies indicates a possible relationship between the particular proteins affecting geotaxis behavior. We noticed significant patterns in five fly lines. However, final statistical analysis has not been complete for all mutant runners.