3. Which of the following is/are TRUE? (Select ALL that are
TRUE.)

a. Activation of the MAP kinase pathway drives entry into the
cell cycle by promoting degradation of S cyclin protein, which is
at highest levels in G1 and low levels in S phase.

b. The cyclin-dependent kinase S-Cdk is active only when bound
in a complex with S cyclin.

c. The anaphase promoting complex (APC) advances the cell cycle
from metaphase to anaphase by adding polyubiquitin to targets, such
as cyclin, which are then degraded in the proteasome.

d. Chromosomes migrate to the poles of the mitotic spindle
during anaphase on interpolar microtubules.

e. An interpolar microtubule within the mitotic spindle has its
minus end attached to one centrosome and its plus end attached to
the other centrosome