VDR and vitamin D deficiency: (4) Vitamin D Receptor (VDR) Upregulation: Lactoferrin enhances VDR expression in osteoblasts, thereby amplifying vitamin D signaling and improving osteoblast function and bone density under vitamin D deficiency conditions.(5) Autophagy Activation and Angiogenic Factor Induction: Lactoferrin promotes osteogenic differentiation by inhibiting BCL2 expression and enhancing Beclin1-dependent autophagy activity.