Functionally, the TPTEP1/miR-548d-3p/KLF9/PER1 axis reduces gastric cancer cell migration and invasion, with KLF9 serving as the critical regulatory node that translates the long non-coding RNA TPTEP1’s tumor-suppressive effects into PER1-mediated anti-metastatic activity. The gene discussed is TPTEP1; the disease is gastric cancer.