ACTN3 and cancer: The gene signature constructed in this study was based on seven differentially expressed lactate metabolism-related genes screened from TCGA cancer samples: actinin alpha 3 (ACTN3), SLC16A1, SLC16A3, LDHA, LDHD, HAGH, and DARS2. ACTN3, a structural protein of the Z-line of fast skeletal muscle fibers [56], maintains the orderly arrangement and normal contraction of muscle fibers by cross-linking with fine muscle filaments.