LMNA and progeroid syndrome: Immunofluorescence microscopy using a lamin A specific antibody (not detecting progerin) revealed that nucleoplasmic lamins are still present in mid-passage progeria cells (HGPS 1 at p17 and HGPS 2 at p15), but absent in late passage HGPS 2 (p21) cells (Fig. 3B,C; Fig. S3).