SPHK1 and posterior cortical atrophy: We demonstrated that SphK1 gene knockout or enzymatic inhibitors (such as FTY720 and SKI‐II) could significantly decrease neurosphere formation in IIG5 (Figure 3D) and 22RV1 (Figure 3E) cells, indicating the driver role of SphK1 but not of Sphk2 in NED of PCa.