30. During vertebrate limb development, a specialized ectodermal structure, called Apical Ectodermal Ridge (AER), forms at the dorso-ventral ectodermal boundary at the distal tip of the developing limb bud.
    The following experimental facts about the AER is available:
    (A) FGF-2, 4, and 8 are expressed in the AER
    (B) Removal of the AER causes cessation of limb growth
    (C) Removal of AER along with implantation of beads soaked in FGF 8 or
    (D) FGF 4 or FGF 2 protein rescues the AER removal phenotype and gives rise to normal limb
    Which of the following statements cannot be made based on the above facts?
    (1) FGF 2, 4, and 8 are secreted proteins.
    (2) FGF 2, 4, and 8 are necessary and sufficient for AER function
    (3) FGF 2, 4, and 8 are sufficient for AER function
    (4) FGF 2, 4, and 8 have largely redundant functions

---

The apical ectodermal ridge (AER) is a specialized ectodermal structure critical for the growth and patterning of vertebrate limb buds. Several FGFs, primarily FGF2, FGF4, and FGF8, are expressed in the AER and act as secreted signaling molecules essential for maintaining limb bud outgrowth and development.

---

Analysis of Provided Statements

• (A) FGF-2, 4, and 8 are expressed in the AER

• (B) Removal of the AER causes cessation of limb growth

• (C) Removal of AER with implantation of beads soaked in FGF 8, 4 or 2 rescues limb development

• (D) FGFs have redundant functions in the AER

These findings lead to conclusions regarding FGFs and AER:

---

True Statements Based on Experimental Facts

1. FGF2, FGF4, and FGF8 are secreted proteins.

   • These FGFs are secreted signaling molecules produced by AER cells that maintain underlying mesenchyme proliferation and limb outgrowth.

2. FGF2, FGF4, and FGF8 are sufficient for AER function.

   • Implantation of FGF-soaked beads can rescue limb growth after AER removal, demonstrating sufficiency to replace AER signals for limb outgrowth.

3. FGF2, FGF4, and FGF8 have largely redundant functions.

   • These FGFs can substitute for each other in maintaining limb outgrowth, indicating functional redundancy.

---

Statement That Cannot Be Made

• FGF2, 4, and 8 are necessary and sufficient for AER function.

  • Although they are sufficient to stimulate limb outgrowth, the necessity part is more complex. Other molecules and pathways also contribute to AER function; thus, it cannot be concluded solely from the facts given that these FGFs are strictly necessary in all contexts. Their overlapping functions and involvement of other factors complicate the assertion of exclusivity and necessity.

---

Summary and Conclusion

From the provided experimental data, it is clear that FGF2, FGF4, and FGF8 are secreted and sufficient for many aspects of AER function with largely redundant roles in supporting limb bud outgrowth. However, one cannot definitively conclude that they are both necessary and sufficient, considering additional signaling molecules contribute to AER functionality and limb development.

---

Answer:
The statement which cannot be made based on the facts is:
(2) FGF 2, 4, and 8 are necessary and sufficient for AER function.