XDH and breast cancer: Interestingly, although PFKFB4 silencing has been shown to reduce expression of SRC-3 target genes transketolase (TKT), adenosine monophosphate deaminase (AMPD1) and xanthine dehydrogenase (XDH) in breast cancer cells [17], the expression of these genes were not affected in the GSCs (Fig. S4A), suggesting that the mechanism of PFKFB4 in GSC survival is likely to be independent of SRC-3.