To further investigate whether the succinate and other metabolites within the TCA cycle were accumulated due to the observed altered regulation of genes for SDHs and other enzymes in the cycle (as shown in Fig. 3), we conducted liquid chromatography-mass spectrometry (LC–MS) analysis to measure the levels of various metabolites in PDLIM2-knockdown lung cancer cells. The gene discussed is PDLIM2; the disease is lung carcinoma.