CSTA and neoplasm: Figure 2 shows the intensity of cystatin A as measured by MALDI-TOF MS. Interestingly, tumor burden as measured by in vivo imaging system in mouse 902 appeared to plateau and slightly decrease after day 42 (supplemental Fig. S2). A similar trend was observed in cystatin A intensity for mouse 902 as detected by MALDI-TOF profiling (Fig. 2, A and B).