FAS and steatosis: Analysis of mRNA levels of several steatosis markers revealed a significantly higher expression of cluster of differentiation 36 (CD36) in livers of young mice fed WD as compared to the SFD controls and in the advanced-age mice a higher expression of tumour necrosis factor (TNF) receptor superfamily member 6 (Fas) in the WD group as compared to SFD controls (p = 0.008 and p = 0.005, respectively) (data not shown).