Researchers have successfully identified over 5,000 proteins that are present in embryonic stem cells, tripling the size of previous results and in the process creating the largest quantified protein map to date. Stem cells hold great potential in biology and medicine, but a host of questions lingers about how they operate and convert into other cells. To help answer these questions, researchers have begun taking a 'big picture' approach, identifying all the proteins that are expressed in stem cells. Currently, around 1700 proteins have been identified in stem cells. Now, using mass spectrometry and special "heavy" amino acids (made with...