IGFBP5 and breast cancer: Although IGFBP5 has been associated with various types of cancers, acting in oncogenic or tumor-suppressive roles, such as breast cancer [4, 6, 14-16], osteosarcoma [5, 17, 18], head and neck squamous cell carcinoma [19], neuroblastoma [20], or prostate cancer [21], little is known about the role of IGFBP5 in human MM.