Let $n\geq 3$, and $u$ satisfies $$ -\Delta u=K(x)u^{\frac{n+2}{n-2}} \quad x\in B_1\setminus \{0\}, $$ where
- $|K(x)|\leq A$ in $B_1\setminus \{0\}$, and
- $u\geq 0$ in $B_1\setminus \{0\}$.
Can we use the Brezis-Kato theorem to show $u\in L^{\infty}(B_{0.9})$?