1x10^6 A549 cells were intracellularly stained with 0.4 ug CoraLite®594-conjugated Cathepsin L Monoclonal antibody (CL594-66914, Clone:1A12G8)(red), or 0.4 ug CoraLite®594 Mouse IgG2b isotype control (11B8C4) (CL594-66360-3, Clone: 11B8C4) (blue). Cells were fixed with 4% PFA and permeabilized with Flow Cytometry Perm Buffer (PF00011-C).