Furthermore, the MEK1/2 inhibitor, AZD6244, was also able to synergise with AZD5363 in a range of HER2-amplified cell lines, suggesting that activation of ERK signalling in response to AZD5363 treatment may serve as a potential mechanism to limit its efficacy in HER2-amplified breast cancer lines. The gene discussed is MAPK1; the disease is breast cancer.