Question

Given the findings in the passage, which additional result most strongly indicates that the TGFBR1 and TGFBR2 receptors regulate TGFβ-dependent epithelial proliferation?

1) Treatment with TGFBR1 receptor agonist resulted in reduced MIB1 detection.
2) Expression of TGFBR1 and TGFBR2 was observed to increase during intervals of heightened epithelial cell proliferation.
3) Genes for several different receptor subtypes were found in untreated epithelium.
4) Treatment with new TGFBR3 receptor antagonists decreased the number of MIB1-positive cells.

Answer 1

The additional result most strongly indicating TGFBR1 and TGFBR2 regulate TGFβ-dependent epithelial proliferation is the reduced MIB1 detection after treatment with a TGFBR1 receptor agonist.

Step-by-step explanation:

The question asks which additional result most strongly indicates that the TGFBR1 and TGFBR2 receptors regulate TGFβ-dependent epithelial proliferation. The correct answer would be option 1) Treatment with TGFBR1 receptor agonist resulted in reduced MIB1 detection. This is because the reduction in MIB1, which is a marker for proliferation, suggests a direct involvement of TGFBR1 activation in the control of cell proliferation. Option 2) is less definitive as it shows a correlation but not causality; option 3) is not relevant to the regulation mechanism; option 4) introduces another receptor, TGFBR3, which does not answer the question directly about TGFBR1 and TGFBR2.