MS4A1 and metastatic melanoma: Quantitative cytometry of a tissue array from metastatic melanoma patients’ samples showed the presence of CD20+B cells (negative for melanoma-associated markers) in 17/48 lesions (33%; frequency of B cells (0.57%–28.8% of all cells); Fig. 1a, b) and biopsies from further six melanoma patients showed co-localization of IGF-1 in CD20+ B cells (Fig. 1c).