let-7c reduces Aβ production by inducing BACE2 to cut C99. A. 2EB2 cells transfected with pmiR-let-7c or not, and C99 and C83/C80 protein detected by C20 antibody. *P<0.05, let-7c compared to the control group; B. pAPP-C99Flag transfected into HEK293 cells with pmiR-let-7c or not, and C99 and C83/C80 protein detected by C20 antibody. *P<0.05, let-7c compared to the control group; C. pAPP-C99, pAPP-C99 and pshBACE2, pAPP-C99 and pshNCT transfected into HEK293 cells with pmiR-let-7c or not, and C99 protein detected by C20 antibody. *P<0.05, let-7c compared to the control group; D. pAPP-C83, pAPP-C83 and pshBACE2, pAPP-C83 and pshNCT transfected into HEK293 cells with pmiR-let-7c or not, and C83 protein detected by C20 antibody. *P<0.05, let-7c compared to the control group; E. HEK293 cells transfected with pKv2.1-Flag and pmiR-let-7c or not, and KCNB1 protein detected by M2 antibody. *P<0.05, compared to the control group. Values represent means ± SD, n=3.