COL1A1 and osteoporosis: To directly test the role of osteoblast Gpx4 suppression in ferroptotic osteoporosis, we generated a strain of osteoblast-specific Gpx4 knockout mice by crossing Gpx4fl/fl mice with Col1a1-Cre mice, supposedly resulting in the deletion of exons 2–4 of the Gpx4 gene in osteoblasts (Fig. 7a).