BCL2L1 and neoplasm: On the one hand, MSCs can promote tumor initiation and development by: 1) suppressing the immune response and enhancing the invasiveness of tumor cells (73); 2) secreting multiple trophic factors and cytokines to promote tumor vascularization (74); 3) increasing tumor cell drug resistance by paracrine mechanisms (75); 4) stimulating tumor cells to secrete Bcl-2 and Bcl-XL and inhibiting their apoptosis (76); and 5) transforming into tumor-associated fibroblasts (77).