What is released to stimulate osteoclasts?

Osteoclasts are stimulated by several factors, primarily by the receptor activator of nuclear factor kappa-Β ligand (RANKL), which is produced by osteoblasts and other cells in the bone. Additionally, parathyroid hormone (PTH) can enhance osteoclast activity indirectly by promoting the expression of RANKL. Other factors such as calcitriol (active vitamin D) and cytokines like interleukin-1 (IL-1) can also contribute to the stimulation of osteoclasts.