As expected, the fluorescence intensity of progerin in the HGPS fibroblasts was higher than that in the normal fibroblasts; however, the fluorescence intensity was quite variable among the HGPS fibroblasts (Fig 1A and B, Appendix Fig S1), which may be because the expression level of progerin is age‐dependent and cumulative with cell passages in HGPS patient‐derived fibroblasts (Goldman et al, 2004). This evidence concerns the gene LMNA and Hutchinson-Gilford progeria syndrome.