Question

AKT promotes the survival of many cells. It is activated by an intracellular signaling pathway that is triggered by an RTK that activates PI-3-kinase. Which of the following is FALSE?

1) AKT promotes cell death
2) AKT is activated by an RTK
3) AKT activation requires PI-3-kinase
4) AKT promotes cell survival

Answer 1

Statement (1) is FALSE because AKT promotes cell survival rather than cell death. Abnormalities in the MAPK pathway that can cause uncontrolled cell proliferation include mutations in RTKs, constitutive activation of RAS, and overexpression of MAP kinase.

Step-by-step explanation:

The student asked which statement is FALSE regarding AKT and its role in cell survival signalling pathways activated by receptor tyrosine kinases (RTKs) and PI-3-kinase. The statements given were: (1) AKT promotes cell death, (2) AKT is activated by an RTK, (3) AKT activation requires PI-3-kinase, (4) AKT promotes cell survival. Of these, statement (1) is FALSE because AKT is well-known for promoting cell survival, not cell death; this is in direct contradiction with statement (4), which is true.

To explore scenarios leading to uncontrolled cell proliferation due to abnormalities in the MAP kinase (MAPK) pathway, consider the following:

• A mutation that leads to constant activation of an RTK, which would mean continuous signalling even without growth factors,
• Constitutively active RAS protein due to a mutation, leading to relentless activation of the MAPK pathway,
• An overexpression of MAP kinase, causes increased and unregulated cell division signals.

Each of these scenarios can potentially result in uncontrolled cell proliferation, a hallmark of cancer.