APP and infection: Exploring this further, and validating the biological relevance of secretase-mediated APP processing in Gag-transfected 293T cells, infection of differentiated THP-1 cells with HIV-1 pseudotyped with VSV-G envelope, to attain high multiplicity of infection (m.o.i), also resulted in decreased abundance of APP and CTFs that could be blocked by inhibiting γ-secretase (Fig. 5e).