Liver transferrin mRNA levels, serum transferrin levels, and correlation between erythrocyte protoporphyrin and serum transferrin in BALB/c mice. (A) Quantification of liver transferrin mRNA by qRT-PCR. (B) Serum transferrin levels in BALB/c female mice, either wild-type control littermates (wt) or fch/fch mice, and in control mice before [C] or after [C+PPIX] PPIX injections. Results are expressed as mean ± SD for at least 6 mice per group. Serum transferrin levels and liver mRNA expression were significantly increased in fch/fch and in PPIX-injected control mice. (C) A highly significant correlation was observed between erythrocyte PPIX and serum transferrin (r²  = 0.86) across the 4 groups of mice: wt (•), fch/fch (○), BALB/c (♦), and BALB/c + PPIX (▵). (D) Quantification of transferrin mRNA by qRT-PCR in HepG2 cells grown in the absence (0) or in the presence (24 h, 48 h) of 30 μM PPIX for 24 or 48 hours.