S1PR3 and osteosarcoma: Methods: The effects of KRX-725-II and its derivatives, Tic-4-KRX-725-II and [D-Tic]4-KRX-725-II—pepducins acting as S1PR3 antagonists as allosteric modulators of GPCR activity—were tested on metastatic osteosarcoma cells (143B) for proliferation and migration inhibition.