To do so, we adapted our previously developed quantitative immunocytology (IC) assay17 to detect early DCCs using melanoma-associated chondroitin sulfate proteoglycan (MCSP), a cell surface marker chosen for both its ability to enable transcriptomic analysis and its expression in melanoma circulating tumor cells and DCCs with tumor-forming potential2,18. The gene discussed is CSPG4; the disease is melanoma.