We investigated genes expression by retrograde axonal transport of replication-defective adenoviruses carrying genes for LacZ (AdLacZ) and Bcl-2 in motor neurons of transgenic mice expressing mutant human Cu/Zn superoxide dismutase (SOD1) gene containing a substitution of alanine for glycine at position 93. We found that intramuscular injection of AdLacZ into the tongue of mutant SOD1 transgenic mice and their wild-type littermates at various ages results in high expression of the transgene and similar time course of expression in hypoglossal cranial nerve nuclei, suggesting no difference in the behavior of the transgene expression between the two groups. Subsequently, we employed a molecular switching cassette for Bcl-2 designed to express Bcl-2 by Cre-loxP recombination using adenoviral vectors, and examined the COS7 and primary neuronal cells with the mutant SOD1 gene. The overexpression of Bcl-2 in