It has been shown that in the absence of glucose, glutamine serves as a major energy source in cancer cells.19,34 Similarly, cancer cells can also metabolize lactate and fatty acids, under metabolic stress, to derive ATP.33,35 Our results demonstrate that activation of AMPK is required for the metabolism of these substrates as cells lacking functional AMPK fail to grow in the presence of these substrates. Here, PRKAA1 is linked to cancer.