ATP flux was examined by luminometry, as previously described5 (link),46 (link). Primary calvarial cells isolated from Panx3 KO mice were seeded at 104 cells/well in a 96-well plate, and induced by osteogenic culture media for 14 days. The cells were then washed with PBS, followed by incubation in PBS for 2 min. The supernatant was collected and assayed with luciferase and luciferin (Promega). The luminescence was measured using an Infinite 200 PRO (TECAN).