Moreover, Chang et al.109 discovered that adipose tissue-derived mesenchymal stem cells (AT-MSCs) obtained from type 2 diabetes mellitus (T2DM) donors differentiate into cancer-associated fibroblasts (CAFs) when co-cultured with BCCs under hypoxic conditions, in turn promoting BCC proliferation and in vivo metastasis, as well as the expression of fibroblastic markers, which was associated with TGFβ-Smad2/3 signal activation. Here, SMAD2 is linked to type 2 diabetes mellitus.