Plays a redundant role in promoting the expression of calcium channel CACNA1S at the cell membrane, and thereby contributes to increased channel activity. Slows down the inactivation rate of the calcium channel CACNA1C. Negative regulator of osteoclastogenesis. Following TNFSF11/RANKL stimulation, interacts with TNFRSF11A/RANK and interferes with the formation of the TNFRSF11A signaling complex, leading to the suppression of TNFSF11-initiated NF-kappa-B and MAPK signaling pathways. Impairs TNFSF11-induced, BTK/TEC-catalyzed PLCG2 phosphorylation and activation (By similarity). . This is the function of STAC2 (SH3 and cysteine rich domain 2, Ensembl gene identifier ENSG00000141750).