Figure 5. In vivo and primary cell age-dependent ELF5 and IGFBP6 expression were recapitulated from in mixed age co-culture. Mixed combinations of MEP and LEP from different aged donors demonstrates that age is the important determinant of ELF5 and IGFBP6 expression. Bar graphs showing (A) ELF5 and (B) IGFBP6 gene expression after 10 days in co- culture with different combinations of young LEP and young or old feeder MEPs. Gene expression was normalized to RPS18. (C and D) Age-dependent expression levels of the two genes in co-culture recapitulate 4p and primary HMEC. Lineage-and age-dependent ELF5 or IGFBP6 gene expression was shown by dot plots in (C) 4p HMEC and in (D) breast tissues. * and ** showed statistical significances at p<0.05 and p<0.01, respectively.