Western blot analysis: The extracts of 293T, MCF7, HT-29, HL-60, HeLa, mouse brain, and rat brain were resolved by SDS-PAGE, transferred to PVDF membrane and probed with anti-human HtrA2/Omi antibody (1:1,000). Proteins werevisualized using a goat anti-mouse secondary antibody conjugated to HRP and an ECL detection system.