PIK3CA E545K mutants induce epidermal growth-factor independent proliferation of HER2 L755S mutants through a contact-mediated mechanism. We used RT2 Profiler PCR Arrays to study changes in gene expression in the HER2 L755S mutants when co-cultured with the PIK3CA E545K mutants and compared it to the HER2 L755S mutants grown in isolation. Overall design: There are two groups. HER2 L755S mutants were co-cultured with PIK3CA E545K mutants. The co-culture was then flow-sorted to separate the HER2 L755S mutants. The flow-sorted HER2 L755S mutants were the test group. HER2 L755S mutants grown in isolation were used as the control group. Each group (test and control) had two biological replicates and each biological replicate had two technical replicates (quadrapilcates for each group in total).