Introns 10 and 11 and the last 150 nucleotides of exon 11 were deleted, thereby abolishing production of lamin C and producing a mutated prelamin A that precludes wild-type Lmna synthesis. A point mutation in exon 12 resulted in the amino acid substitution of leucine for methionine within the CaaX motif. This substitution triggers protein geranylgeranylation. A floxed neo cassette downstream of exon 12 was used for selection. (J:146099)