Figure 4. 4-HPR and 4-HBR changed the expression of specific apoptosis-related genes. Bar charts present the results from quantitative PCR analysis of CASP8, DDIT4, DR4, DR5, DR6, NOXA, PLAB, and OPG mRNA from MCF-7, T-47D, and MDA-MB-231 cells treated with vehicle, 4-HPR, or 4-HBR (31.6 μM). Values are normalized to β-actin and expressed as fold-change from vehicle-treated control cells. The graphs are representative of 3-4 independent experiments experiments and t-test was performed for statistical analysis (*p≤0.05, **p≤0.01, ***p≤0.001, ****p≤0.0001). 4-HPR, N-(4-hydroxyphenyl)retinamide; 4-HBR, 4-hydroxybenzylretinone; CASP8, caspase 8; DDIT4, DNA damage-inducible transcript 4 protein; DR4, death receptor 4 or tumor necrosis receptor superfamily member 10A, TNFRSF10A; DR5, death receptor 5 or tumor necrosis factor receptor superfamily member 10B, TNFRSF10B; DR6, death receptor 6 or tumor necrosis receptor superfamily member 21, TNFRSF21; NOXA, phorbol-12-myristate-13-acetate induced protein 1; PLAB, placental bone morphogenetic protein; OPG, osteoprotegerin.