IGFBP5 and breast cancer: Daily subcutaneous injections of recombinant IGFBP5 protein stimulate osteoblast activity and bone accretion in ovariectomized mice.6 Moreover, a previous study demonstrated that IGFBP5 plays a crucial role in the carcinogenesis and progression of several types of cancer, such as oral and breast cancer, and its expression is usually dysregulated.7, 8, 9 However, the effect of IGFBP5 on the regulation of proliferative and apoptotic activities in NP cells is not well defined, even though IGFBP5 is expressed in NP cells.