Fyn positively regulates the activation of DAP12 and FcRγ-mediated costimulatory signals by RANKL during osteoclastogenesis

► Fyn is critical for osteoclast differentiation. ► Fyn positively regulates the activation of Syk, PLCγ2, and Gab2. ► Fyn relays RANK/RANKL signal to the costimulatory DAP12/FcRγ-mediated signals.