Extended Data Fig. 2: M-L6-IL12 is cleaved by mouse tumors ex vivo and in vivo.

a, Masked IL-12 variants containing linkers L2, L4, L6 and the non-cleavable LNC (0.83 μM) were incubated with EMT6 homogenate (2 mg/mL) for 6 hr at 37 °C. Samples were then diluted in media and applied to pre-activated mouse CD8+ T cells and pSTAT4 MFI was measured. b, M-L6-IL12 or non-cleavable M-LNC-IL12 were incubated in tumor-bearing serum or EMT6 homogenate for indicated times at 37 °C. Reaction mixture was analyzed via western blotting. MMP2-activated M-L6-IL12 is shown as positive control. c, B16F10-bearing mice were injected intratumorally with either M-L6-IL12 or M-LNC-IL12 (167 pmol). Tumors were collected 2 hr post injection and homogenized immediately in the presence of proteases inhibitors and EDTA to stop any further degradation and analyzed via western blotting. Experiments were performed twice with similar results.