BRCA2 and cancer: It is worth noting that deficiency of each of these gene products (PTEN, BRCA1, BRCA2 and ARID1A) has been previously shown to render cancer cells responsive to PARP inhibition [23, 25, 31, 34], and may in this case collectively contribute to the superior sensitivity of IGROV1 cells to Olaparib when used in combination with PI3K inhibitor [34].