ALK and neoplasm: Beginning at 3.5 weeks after tumor induction, when tumors are at an early stage of progression25, we intratracheally administered the nanosensor panel into Eml4-Alk and healthy control mice, and observed that several nanosensors were differentially cleaved by proteases in the pulmonary microenvironment (Fig. 2c), enabling differentiation of tumor-bearing and healthy mice at an early stage of tumor progression (Fig. 2d).