The equation is ∂ ∂ t u = 1 2 Δ Δ u + c sin ⁡ ⁡ ( β β u + θ θ ) + ξ ξ , where c , β β , θ θ are real-valued constants, and ξ ξ is space-time white noise. The space dimension is fixed to 2. In the proof of existence of solutions, the thresholds β β 2 = n n + 1 8 π π again play a role in determining convergence of certain terms.