Although PLK4 has been found to be overexpressed in a number of adult peripheral tumors like colorectal [20], breast [21], lung [22], melanoma [23], leukemia [24], and pancreatic cancer [25], we were the first to report PLK4 overexpression in embryonal tumors and in pediatric brain tumors [7,10,11]. Here, PLK4 is linked to leukemia.