APPL1 and breast cancer: GSEA of the RNA-seq data obtained in 47 breast cancer cell-lines (Supplementary Figure S9) [9] grown under standard conditions indicates that constitutive expression of the “MHC1-APPL” and “IFNα-Response” gene sets is low in highly sensitive cell-lines (ATRA-score > 0.17) and high in their counterparts characterized by low ATRA-sensitivity (ATRA-score < 0.17) (Figure 4C).