Human filamin C (FLNc) is a target of the protease calpain at Y2625. To confirm the dependency of calpain cleavage from FLNc phosphorylation at position S2623/S2624 by PKCa, FLNc was overexpressed in HEK293 cells and cells were treated with PMA to stimulated kinase activity, with Gö6976 to inhibit kinase activity or mock-treated with DMSO. Subsequently, recombinant calpain-1 and GluC were used and the resulting peptide TVTSSSSRGSSY was monitored by SRM analyses.