Candidate gene expression versus mean lifespan I. The expression level of nine candidate genes was examined among 21 BxD mouse strains. Expression data was generated by Williams et al.  (GEO series GSE6621). Lifespans of BxD strains were assayed by Gelman et al. . The dashed horizontal line indicates the average gene expression level for each gene, while the solid line represents the least-squares regression estimate. Individual plots are shown for (A) Hao3, (B) Sult2a2, (C) Spink3, (D) Socs2, (E) Mup4, (F) Igfals, (G) Lifr, (H) Igf1 and (I) Efgr. The spearman rank correlation between expression and mean lifespan is shown in the upper right corner of each plot.