UCHL1 and osteosarcoma: Despite some controversy on the functional role of UCH-L1 in the development of primary tumors, the ability of UCH-L1 to promote malignant progression, namely invasion and metastasis of carcinoma cells, is well documented and includes non-small lung, breast and prostate cancers [18,19,20,21], as well as melanoma [22], cervical carcinoma [23], and osteosarcoma [24].