To emulate the progerin splice variant, 150 bp of the 3' end of exon 11 along with introns 10 and 11 were deleted. A single point mutation (T>A) was also used to create an amino acid substitution of serine for cysteine in the CaaX motif encoded within exon 11. This results in a nonfarnesylated progerin protein. A floxed neo cassette was inserted downstream of exon 12 for selection purposes.