Based on the capability of Sp1 in modulating the expression of Cyclin B1 gene [45], we could conclude that phloretin-induced downregulation of cyclin B1 and cell cycle arrest at G2/M phase in PCa cells was not via the p53/cyclin B1 pathway, but via the Sp1/cyclin B1 pathway. This evidence concerns the gene SP1 and posterior cortical atrophy.