To test whether this growth-promoting effect of LAP2α in progeria cells also varies with progerin levels, we introduced myc-tagged human LAP2α or GFP as a control into progeria cells derived from young patients (HGPS 1, p17; HGPS 2, p15) expressing intermediate levels of progerin (Fig. S1C), and into HGPS 2 at later passages (p21) expressing higher levels of progerin (Vidak et al., 2015). This evidence concerns the gene ZMPSTE24 and progeroid syndrome.