PRKCD and osteoporosis: Our study aimed to investigate the important role of PKC-δ in B cells and its subsequent effects on OC and OB biology by using a Cre-loxP-based conditional knockout (cKO) technology to selectively inactivate PKC-δ in B cells, which could help to shed more light on our understanding of osteoimmunology-related disease, such as rheumatoid arthritis and osteoporosis.