cellular responses to cocaine. The end result of studying tissue lysates from such a heterogeneous structure is that most of the observed effects will be very small since they are averaged together with several other, differently responding, cell types. This is particularly problematic for microarray analyses, which depend on strong effects for statistical significance. One solution that is being currently developed is fluorescence activated cell sorting (FACS) in conjunction with BAC-transgenic mice that express GFP in specific cell types (e.g., dopamine D1 vs. D2 neurons) [86]. This new technology will permit the study of how cocaine alters gene expression and histone modifications in isolated cell populations.
