TGFB1 and Dowling-Degos disease 1: TGFβ is recognized as an anabolic factor in IVD and has been found to prevent DDD.58 However, high levels of TGFβ1 have also been observed in the IVDs from DDD patients.39,40,59–63 One group has previously shown that inhibition of TGFβ can prevent DDD, which was attributed to a change in pSmad1/5/8 to pSmad 2/3 downstream signaling.64 The various effects of TGFβ are likely related to the concentration of TGFβ.