To confirm this finding, TOP-flash plasmid (a luciferase reporter plasmid that contains two sets of 3 copies of the wild-type TCF binding regions) was transfected to primary PCa sphere-derived cells to monitor the effect of luteolin on the transcriptional activity of β-catenin (the transcriptional co-activator and the output of Wnt signaling) and the cells transfected with FOP-flash plasmid which contains mutated TCF binding regions were used as negative control. This evidence concerns the gene HNF4A and posterior cortical atrophy.