Curcumin and a PKC-specific inhibitor block IGF-1- and RA-induced secretion of sAPLP2. A, relative abundance of sAPPα, sAPLP2, and sAPLP1 in culture medium, normalized to the relative abundance of full-length APP, APLP2, or APLP1 in cell lysates from SH-SY5Y cells treated with 10 nm IGF-1 for 18 h in the absence or presence of 5 μm curcumin or 5 μm bisindolylmaleimide XI (BIM11) for the last 18 h. B, representative Western blot analyses of secreted and full-length APP, APLP2, and APLP1 after IGF-1 treatment. C, relative abundance of APPα and sAPLP2 in culture medium, normalized to the relative abundance of full-length APP or APLP2 in cell lysates from SH-SY5Y cells treated with 1 μm RA for 6 days in the absence or presence of 5 μm curcumin or 5 μm bisindolylmaleimide XI for the last 18 h. D, representative Western blot analyses of secreted and full-length APP and APLP2 after RA treatment. Data represent mean ± S.E., n = 4–7. *, p < 0.05 and **, p < 0.01 significantly different from cells treated with IGF-1 or RA. Untreated control (C) cells are included for comparison. The vertical lines indicate the quantified bands.