AKT1 and neoplasm: Figure 5D demonstrates that lapatinib or MRK-003 GSI treatment alone decreased PY-ErbB-2 protein 40% compared with vehicle control. Interestingly, lapatinib plus GSI treatment, unlike trastuzumab, had little effect on PY-ErbB-2 protein. However, both phosphorylated ERK-1/2 and AKT1 proteins were reduced in tumours treated with lapatinib plus GSI compared with all other treatments (Figure 5D).