SIRT6 and cancer: Since the levels of SIRT1 and SIRT6 do not change in response to lapatinib treatment, they are unlikely to have a direct role in modulating lapatinib signaling but may instead play a part in fine-tuning FOXO3 acetylation and therefore lapatinib sensitivity by setting the baseline for the de-acetylation activity in both lapatinib sensitive and resistant cancer cells.