Viagra causes dilation of blood vessels and increased blood flow to the penis, facilitating erection. Viagra acts by inhibiting which of the following events?

#Question id: 1403

#4. Cell Communication and Cell Signaling

Tumor-suppressor genes encode proteins with which of the following functions?

a. growth-promoting               b. growth-arresting                  c. pro-apoptotic

d. anti-apoptotic                      e. DNA repair

#Question id: 1404

#4. Cell Communication and Cell Signaling

Which of the following are transcription factors?

#Question id: 1405

#4. Cell Communication and Cell Signaling

A gain-of-function mutation in which of the following would have the same effect as a gain-of-function mutation in Ras?

#Question id: 1406

#4. Cell Communication and Cell Signaling

Which of the following is a consequence of p53 stabilization?

a. stabilization of Cdc25A      b. activation of ATM                c. blocked apoptosis

d. transcription of p21                        e. DNA repair

#Question id: 1407

#4. Cell Communication and Cell Signaling

Which of the following is pro-apoptotic?

a. Bax              b. Bcl-2                       c. p53              d. protein kinase B      e. PTEN

#Question id: 1408

#4. Cell Communication and Cell Signaling

Human papilloma virus encodes proteins that inhibit the function of

a. Bcl-2.           b. Myc.                        c. p53.             d. PDGF receptor.      e. Rb.