TGFB1 and disease of the tendon: Excessive or repetitive mechanical loading is the most common cause of tendinopathy.[28] Our study and previous studies have found that tenocytes and TSPCs are the effector cells in response to mechanical loading.[6, 32] In normal physiological situations, appropriate mechanical loading produced by body weight and muscle force is necessary to activate TGF‐β, which modulates several essential cellular processes in tissue development, differentiation, and homeostasis.