Stat3 upregulates the expression of lysosomal proteases cathepsin‐B and cathepsin‐L under physiological conditions (Kreuzaler et al., 2011) and, thus, may facilitate cathepsin‐B enhanced tissue invasion and lysosomal‐mediated cell death regulation in brain tumors (Levicar et al., 2002). The gene discussed is CTSL; the disease is brain neoplasm.