H2AX and lymphangioleiomyomatosis: As further confirmation of this hypothesis, a significant decrease of the positivity to the SA-β-galactosidase staining was observed in tuberin-expressing LAM/TSC cells following 5-azacytidine treatment (Figure 2c), while the induction of tuberin only slightly reduced the cells positive to phospho-histone H2A.X (5%) compared to tuberin null LAM/TSC cells (7.8%) analysed by flow cytometry (data not shown).