Co-culture experiments with tumor cells and NETosing neutrophils have hinted toward tumor-supplied factors, such as G-CSF, IL-8, or cathepsin C (Alfaro et al., 2016; Demers et al., 2012; Demers et al., 2016; Park et al., 2016; Xiao et al., 2021), but deeper mechanistic insights are needed to dissect contributions from developmental and diurnal neutrophil states. Here, CTSC is linked to neoplasm.