Final answer:
The cell-surface glycoprotein that is characteristic of stem cells but stops being expressed when a cell has committed to the T-cell developmental pathway is CD34.
Step-by-step explanation:
The cell-surface glycoprotein that is characteristic of stem cells but stops being expressed when a cell has committed to the T-cell developmental pathway is CD34.
CD34 is a marker of hematopoietic stem cells and is often used to identify these cells in research and medical settings. As the stem cell commits to the T-cell lineage, CD34 expression is downregulated.
Other cell-surface glycoproteins like CD2, CD3, CD25, and MHC class II are involved in T-cell development and function, but they are not specific to stem cells or indicative of commitment to the T-cell pathway.