Conditional deletion of RANKL using osterix-Cre (active in late proliferating chondrocytes and early differentiating osteoblasts) or osteocalcin-Cre (active in mature osteoblasts) produced transgenic mice with defective tooth eruption, severe osteopetrosis, and unresorbed calcified cartilage. Here, TNFSF11 is linked to osteopetrosis.