CCR1 and neoplasm: To understand the role of these receptors on myeloid cell composition and function at the tumor site, we employed the previously characterized 4PD nanoplatform to silence in vivo CCR1, 2, 5 and 7.20 On injection in BALB/c mice bearing the 4T1 carcinoma, this nanoparticle recognized preferentially (p<0.001) tumor-infiltrating myeloid cells as determined by three way-ANOVA using tissues, leukocyte subsets (CD45− vs CD45+CD11b− vs CD45+CD11b+), and treatment as factors.