ERBB2 and cancer: None of the above studies specifically focused on HER2 + breast cancer and while several hypotheses have been put forth to explain this aberrant choline metabolism in more aggressive tumors (to provide cancer cells with more energy, membrane components for proliferation, restructure membranes to facilitate migration, provide bioactive signaling lipids, or to reshape and prime the microenvironment for invasion), the underlying mechanism is still to be elucidated.