CHRDL1 and osteoporosis: LBP suppresses the PA-induced osteoblast apoptosis via the miR-200b-3p/Chrdl1/PPARγ axis to play a protective role for obesity-induced osteoporosis, but miR-200b-3p/Chrdl1/PPARγ is not the only mechanism for LBPs protecting osteoblasts from PA.