Compared with the cells transfected with an empty control vector, the SIRT4-Flag cell lysates precipitated SIRT4 itself as expected, as well as several other candidates, including MCCC2, which plays a critical role in BCAA metabolism and HCC development 32, as revealed by mass spectrometry analyses of the bands indicated in Figure 3C. The interaction between SIRT4 and MCCC2 was further verified through co-immunoprecipitation (Co-IP) followed by Western blot assays in 293FT cells transiently transfected with SIRT4-HA and MCCC2-Flag. Here, MCCC2 is linked to hepatocellular carcinoma.