Tumor-associated macrophages (TAMs) are key regulators of the tumor microenvironment (TME), but their heterogeneity, driven by tumor-derived cues, poses challenges for therapeutic targeting and underscores the need for precise macrophage reprogramming strategies. Through a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screen, Marelli et al. identified chemosensors as lipid-sensing regulators of macrophage activity, revealing new therapeutic avenues.