N249Q/R345W F3 requires GRP94 ATPase activity for efficient secretion. A) ARPE-19 cells expressing WT, N249Q, R345W, or N249Q/R345W F3 were treated with DMSO or 17-AAG (1 μM) for 24 h and F3 was IP’d from the conditioned media, followed by Western blot analysis. Representative data of 3 independent experiments. B) Quantification of F3 secreted protein levels after treatment, n = 3 (**P ≤ 0.01, t test).