TGFB1 and Dowling-Degos disease 1: Mechanical loads are one of the most important etiologies of DDD.50 In normal physiological situations, appropriate mechanical loading produced by body weight and muscle force is necessary to activate TGFβ in the NP to modulate anabolic activity of NC cells and maintain IVD homeostasis, similar to its role in homeostasis of the bone and cartilage.40,51–53 However, in pathological conditions, as we found in the present study, compression stresses activate excess TGFβ and result in accelerated functional transition of NC cells, leading to pathologic changes of IVD.