SMURF1 and thyroid cancer: Because previous studies suggested that the expression of the tumor suppressor Kisspeptin-1 was downregulated in thyroid cancer [23,24] and that the downregulation or absence of Kisspeptin-1 was involved in thyroid tumorigenesis, invasion, and metastasis [25], the authors next examined whether the increased Smurf1 expression may be involved in downregulated Kisspeptin-1 expression.