Cancer cells (CD45−CD31−) and macrophages are the most prevalent cell populations in the EMT6 tumor model and have been reported to endocytose albumin in tumors.39, 40 Evaluating nAlb-Cy5 uptake within specific cell populations, we found that ~ 5–10% of cancer cells (CD31−CD45−), macrophages (CD11b+F4/80+), and dendritic cells (CD11c+) were Cy5+ with a higher (~ 15–20%) frequency of Cy5+ CD45−CD31+ endothelial cells and neutrophils (Fig. 2l). The gene discussed is ALB; the disease is cancer.