Anhydrotetracycline is primarily used in molecular biology as an inducer in gene expression systems, especially in tetracycline-regulated (Tet-On/Tet-Off) expression systems. It binds to tetracycline-controlled transactivators, enabling precise control of target gene transcription in mammalian, yeast, and bacterial cells. Unlike tetracycline or doxycycline, it is not used as an antibiotic due to lack of antimicrobial activity, making it ideal for research applications where background antibiotic effects must be avoided. Its ability to rapidly enter cells and reversibly regulate gene expression makes it valuable for studying gene function, protein production, and cellular processes in a controlled manner.