SFRP2 and posterior cortical atrophy: Indeed, SFRP1 and SFRP2 mRNA and protein expression were both downregulated in PHF21B-transduced PCa cells but upregulated in PHF21B-silenced PCa cells compared with control cells, revealing that SFRP1 and SFRP2 might be transcriptionally downregulated by PHF21B in PCa cells (Fig. 6a-d).