NAMPT and breast cancer: To explore whether visfatin promoted progression of different subsets of breast cancer cells through stimulation of tumor stromal cells such as macrophages, we indirectly co-cultured human monocytic cell line THP-1 with breast cancer cell lines MDA-MB-231 and MCF-7 for 24 h after pretreatment with or without visfatin 300 ng/mL for six days.