SFRP1 and posterior cortical atrophy: In addition, individual silencing of SFRP1 or SFRP2 potently rescued the TOP/FOP luciferase reporter activity and self-renewal ability in PHF21B-silenced cells (Fig. 6g-h and Additional file 5: Figure S1a-b), revealing that SFRP1 and SFRP2 were functional effectors of PHF21B on regulating Wnt/β-catenin signaling and stem cell-like phenotype in PCa.