PMAIP1 and head and neck squamous cell carcinoma: Combination of NOXA or fenretinide with the BCL-XL specific inhibitor A-1331852, but not with the BCL-2 specific inhibitor ABT-199, showed similar amounts of cell death as compared to ABT-263 (Fig 7), strongly suggesting that the inhibition of MCL-1 and BCL-XL is sufficient to induce cell death in HNSCC cells.