Abstract: Embodiments of the invention include using molecular biology techniques to produce a fusion or chimeric protein of two or more different IGFBPs For example, the IGF binding properties or characteristics of a first protein are retained as is the receptor binding properties and characteristics of a second IGFBP. In particular aspects, a fusion or chimera of IGFBP-6 and IGFBP-3 (IGFBP-6/3) may be produced and used. Certain properties of each binding protein contribute to the therapeutic property of the fusion protein. For IGFBP-3 these properties include the specific binding to a target cell and the induction of apoptosis in a target cell. For IGFBP-6, these properties include an increased affinity for IGF-II versus IGF-I. The binding of IGF-II can deprive a cell exhibiting aberrant growth characteristics of the growth promoting functions of IGF-II.