CTSS and cancer: Furthermore, TAMs are known to upregulate the expression of cysteine cathepsins,[9] which 1) facilitates further recruitment of monocytes from circulation to the TME,[10] and 2) protects tumors from the effect of some chemotherapeutic drugs.[9] Fluorescent probes including cell‐targeting peptide structures[11] or chemokine proteins[12] as well as cathepsin‐reactive activity‐based probes[13] have been used to image cancer models, yet there are no examples of cathepsin‐activatable chemokines as dual‐selective AND‐gate probes to target subsets of macrophages in tumors.