The insulin-like growth factor-II/mannose-6-phosphate receptor is present in fetal bovine tissues throughout gestation.

The insulin-like growth factor-II (IGF-II) and the IGF-II/mannose-6-phosphate (M6P) receptor are thought to play an important role in fetal growth and development. We have studied the expression of the IGF-II/M6P receptor in fetal bovine tissues from 5 through 36 weeks' gestation. Tissues from bovine fetuses were extracted in buffer containing 2% Triton-X-100 and 2% sodium dodecyl sulfate (SDS).

Human osteosarcoma (U-2 OS) cells express both insulin-like growth factor-I (IGF-I) receptors and insulin-like growth factor-II/mannose-6-phosphate (IGF-II/M6P) receptors and synthesize IGF-II: autocrine growth stimulation by IGF-II via the IGF-I receptor.

Unlabelled: Recently, insulin-like growth factor-I and -II (IGF-I and -II) have been implicated in the growth promotion of tumors in vivo and tumor cells in vitro. We have studied the human osteosarcoma cell line U-2 OS in order 1) to gain more insight into the growth promoting actions of the IGFs and 2) to establish an in vitro tissue culture model of IGF action in human tumor cells. Specific binding of 125I-IGF-I and 125I-IGF-II to IGF-I receptors and IGF-II/mannose-6-phosphate (M6P) receptors on U-2 OS cells was demonstrated in competitive binding experiments and in affinity crosslinking experiments.