USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

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What specific marker is commonly used to identify Bone Marrow Stem Cells?

  1. CD19

  2. CD34

  3. CD56

  4. CD68

The correct answer is: CD34

The specific marker commonly used to identify bone marrow stem cells is CD34. This cell surface glycoprotein is expressed on hematopoietic stem cells, which are the precursor cells in the bone marrow responsible for the generation of all blood cell types. CD34 is crucial in both identifying and isolating these stem cells for research and therapeutic purposes. In contrast, other markers listed do not serve this primary function. CD19 is a marker for B lymphocytes, CD56 is associated with natural killer (NK) cells, and CD68 is a marker for macrophages. None of these markers are indicative of hematopoietic stem cells, thereby emphasizing the specific role of CD34 in identifying bone marrow stem cells.