Left: The upper graph indicates the averages expression levels of the RARα protein in T1-T3 cell lines. The middle and lower graphs indicate the average expression levels after stratification of the cell lines for the Luminal (six cell lines in each of the T1 and T3 groups) and the Basal (six cell lines in each of the T1 and T3 groups) phenotype, respectively. Right: The levels of the RARα protein in Basal and Luminal cell lines (upper graph), in ER+, ER−, and Luminal ER−cell lines (middle graph) and the indicated classes of HER2+ and HER2−cell lines (lower graph) are shown. *Significantly different (P-value < 0.05, Student's t-test). **Significantly different (P-value < 0.01, Student's t-test). 