FSTL1 and melanoma: Particularly, the significant roles of a member of the BM-40/SPARC/osteonectin family follistatin-like 1 (FSTL1) in cancer EMT have been widely demonstrated in many types of cancers, such as melanoma [31], esophageal squamous cell carcinoma [32], head and neck squamous cell carcinoma [33], colorectal cancer [34], and lung cancer [35].