Sac2 is a PI 4-phosphatase that specifically hydrolyzes PI(4)P. (A) Mouse tissue lysates were normalized and analyzed by Western blot with specific anti-Sac2 antibody. WBL, whole mouse brain lysate. (B) Different cell lines were harvested and analyzed by Western blot with anti-Sac2 and anti-tubulin antibodies. (C, left) PI phosphatase assay with recombinant Sac2 proteins purified from insect cells. (right) SDS-PAGE analysis of the purified Sac2 samples. (D) Quantification of phosphatase assays shown in C. (E, left) Phosphatase assay with endogenous Sac2 immunopurified by anti-Sac2 antibody. (right) Western blot with anti-Sac2 of the purified protein samples. (F) Quantification of the assay shown in E. Data are from three replicate experiments (mean ± SEM).