BMP4 and osteoporosis: Ectopic expression of circ‐SLC8A1 promoted ALP, BGLAP, SPP1 and BMP4 expression and silenced circ‐SLC8A1 inhibited ALP, BGLAP, SPP1 and BMP4 expression, and it suggested that circ‐SLC8A1 acted as promotive role in the development of osteoporosis.