PRKAA2 and cancer: Overall, these apparently conflicting results can be rationalised by proposing that while AMPK acts as a tumour suppressor that can protect against the development of cancer, once a cancer has arisen it switches from being a tumour suppressor to a tumour promoter, perhaps because it protects tumour cells against the energetic, nutritional or oxidative stresses that they experience due to their rapid growth [30,40].