For instance, Gas2 protein levels were found to increase upon serum starvation in the murine NIH 3T3 cell line 4, 30, and to a lesser extent in embryonal carcinoma F9 cells 21, but not in the murine keratinocyte MSCP5 cells, 31 suggesting the cell specificity of Gas2 function. This evidence concerns the gene GAS2 and embryonal carcinoma.