APOL1 and Hydrocephalus: SPAK is a well characterized intermediating factor in regulating NKCC2 (Slc12a1) and NCC (Slc12a3) expression in renal distal convoluted tubule and thick ascending limb.67 Here we show that the expression of APOL1-G1 activates mTORC2-SPAK pathway in choroid plexus epithelial cells, leading to hydrocephalus.