TFAM and colorectal carcinoma: Additionally, a previous study has reported that mutation of serine-55 to aspartate can mimic the sustained phosphorylation of TFAM because the aspartate residue is negatively charged.19 Consistently, our western blotting analysis clearly demonstrated the phosphomimics of TFAM in MCU-overexpressing CRC cells when serine-55 was mutated to an aspartate residue.