As seen for cervical cancer cells homozygous for the PIK3CA-E545K mutation (Figure 2D), cervical cancer cells expressing PIK3CA-E545K in combination with PIK3CA-wt (HeLa-E545K and CaSki) were more resistant to cisplatin in combination with IR than HeLa cells expressing only PIK3CA-WT (Figure 4 compare black bars in panels A to black bars in panels B and C), confirming that heterozygous expression of PIK3CA-E545K confers resistance to cisplatin, even in the presence of IR. The gene discussed is PIK3CA; the disease is cervical cancer.