PF-4708671 is primarily used in research settings as a selective inhibitor of the p70 ribosomal protein S6 kinase (S6K1). This compound is valuable in studying cellular signaling pathways, particularly those related to the mTOR (mechanistic target of rapamycin) pathway, which plays a critical role in cell growth, proliferation, and survival. Researchers utilize it to investigate the effects of S6K1 inhibition on processes such as protein synthesis, metabolism, and cancer progression. It has also been explored in preclinical studies to understand its potential therapeutic applications in diseases like cancer, diabetes, and obesity, where dysregulation of the mTOR/S6K1 pathway is implicated.