Question

Signal transduction pathways regulate a range of responses in cells. The mitogen-activated protein (MAP) kinase cascade triggered by receptor tyrosine kinases (RTKs) results in cell division. Predict likely scenarios of abnormalities in the MAPK pathway leading to uncontrolled cell proliferation.

a) Increased receptor internalization
b) Impaired kinase activity
c) Enhanced phosphatase function
d) Overexpression of downstream effectors

Answer 1

Abnormalities in the MAP kinase pathway, such as overexpression of downstream effectors, increased receptor internalization, impaired kinase activity, or enhanced phosphatase function, can lead to uncontrolled cell proliferation.

Step-by-step explanation:

Abnormalities in the MAP kinase pathway can have various effects on cell proliferation. One possible scenario is the overexpression of downstream effectors in the pathway, which could lead to an increase in cell division signals, pushing the cell to proliferate uncontrollably. Alternatively, an increase in receptor internalization could enhance the signaling capacity beyond normal levels, also leading to unregulated cell proliferation. Another scenario is impaired kinase activity within the cascade; if the dampening mechanisms are compromised, this could again result in persistent signaling for growth. Lastly, enhanced phosphatase function could attenuate the dephosphorylation of signaling intermediates, prolonging the active state of the pathway and inducing excessive cell division.