Overlay demonstrating the expression of the IGF-1  receptor expression by the 5T2 MM cells. (A) 5T2 MM cells transmigrated in vitro under influence of 5 ng/mL IGF-1 (filled curve) show a clear shift toward a higher expression of IGF-1 receptor  when compared with the cells before migration (open curve). (B) 5T2 MM cells transmigrated in vivo. The expression of the IGF-1 receptor was analyzed before injection (open curve) and 18 hours after injection (filled curve). The majority of 5T2 MM cells express the IGF-1 receptor after injection. These experiments are representative for three independent experiments.