A Key Step in the Development of B Cells Is

question 28

Multiple Choice

A key step in the development of B cells is the expression of the RAG-1 and RAG-2 recombinase proteins. The up-regulation of RAG-1 and RAG-2 in early pro-B cells is induced by:

• A) The cytokine IL-7, which is made by bone marrow stromal cells
• B) The chemokine CXCL12, which is made by bone marrow stromal cells
• C) The B cell-specific transcription factors E2A and EBF
• D) Signaling through the Igα subunit of the B-cell receptor complex
• E) Signaling through the FLT3 receptor tyrosine kinase binding to membrane-bound FLT3

---

Definitions:

Cryptocurrency

Digital or virtual currency that uses cryptography for security, operating independently of a central bank.

Cryptography

The practice and study of techniques for secure communication in the presence of third parties by converting information into a code to prevent unauthorized access.

Money Order

A money order is a payment order for a pre-specified amount of money, serving as a method of transferring or sending money safely where the use of checks or cash is not possible or advised.

Negotiable Instrument

A written document guaranteeing the payment of a specific amount of money to a specified person or the bearer, under certain conditions.