Here we demonstrate in primary HGPS patient fibroblasts and human telomerase reverse transcriptase (hTERT) immortalized fibroblasts that progerin expression down-regulates LAP2α expression at the transcriptional and translational level, causes loss of nucleoplasmic lamin A/C, and leads to impaired cell proliferation. This evidence concerns the gene LMNA and Hutchinson-Gilford progeria syndrome.