PCa cells have been shown to express several factors that regulate osteoclastogenesis, including PTHrP, macrophage colony-stimulating factor (M-CSF), members of the transforming growth factor β (TGF-β) superfamily, and urokinase-type plasminogen activator (uPA-plasmin), resulting in the activation of the matrix metalloproteinases (MMPs; specifically MMP-2 and MMP-9) as well as interleukin-1 (IL-1) and interleukin-6 (IL-6) [16]. Here, IL6 is linked to posterior cortical atrophy.