SMARCA1 and neoplasm: Finally, we also note that the precise composition of the BAF complex and the influence of other driver mutations in ARID1A mutant tumours might also be important in determining the ARID1A/ATR synthetic lethality and our subsequent work will focus on assessing how the balance between the different members of the SWI/SNF complex might modulate the TOP2A defect and ATRi sensitivity.