The diphtheria toxin A gene and a floxed hygro cassette replaced the HS7 (a neuron-specific transcriptional enhancer). A floxed selection cassette was removed by cre-mediated recombination. RT-PCR analysis on whole brain and cerebellum confirmed moderate reduction in transcript expression of all genes in the cluster. However, expression is unaffected in the cortex, hippocampus, and olfactory bulb. (J:177466)