The transgene was generated by placing the L7-deltaAUG promoter enhancer (from the L7-deltaAUG vector in which all upstream ATGs have been mutated) upstream of cre in the pSP-13Cre plasmid. The L7/Pcp2 modified promoter can direct tissue specific expression of genes downstream of it but translation can only be initiated from the ATG of the cre gene downstream of the promoter, resulting in tissue specific expression of cre protein in cerebellar Purkinje cells. (NOTE: A GFP transgene co-integrated with the Tg(Pcp2-cre)1Amc transgene. As such, GFP expression is reported in the cerebellum [personal communication])