<p>(<b>a</b>) Gli36Δ5EGFR cells were incubated with JPM-OEt, a general papain-family inhibitor (+, lanes 2,4 and 6) or 0.1% DMSO vehicle control (−, lanes 1,3 and 5) before the addition of the indicated probe GB119, GB123, or GB125 (the control probe, GB125, contains the Cy5 fluorescence label with a non-reactive amide in place of the acyloxymethylketone (AOMK) “warhead”(22)). (<b>b</b>) <i>In vitro</i> cell labeling with NIRF-APBs. C2C12/ras cells were incubated with JPM-OEt, a general papain-family inhibitor (+) or 0.1% DMSO as a vehicle control (−) before the addition of the indicated probe. Samples were analyzed by SDS-PAGE and Cy5 fluorescence was measured by scanning the gels with a Typhoon scanner. Specific bands are indicated as follows: cathepsin L single-chain form (Cat L sc); cathepsin L heavy-chain (Cat L hc), and cathepsin B (Cat B). (<b>c</b>) Gli36D5EGFR flank tumor tissue was immersed in GB119 for the indicated time or DMSO vehicle control (D) for 30 minutes. Specific cathepsin bands are indicated as follows: cathepsin L single-chain form (Cat L sc,); cathepsin L heavy-chain (Cat L hc); and cathepsin B (Cat B).</p
