Fig 1. Cell viability of malignant peripheral nerve sheath tumor cell line, S462 under the treatment of 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) alone or in combination with doxycycline.

(A), the percentage of S462 cell viability post the treatment of ALA-PDT. The cells were incubated with 1 mM ALA for 24 hours followed by light illumination. The MTT assay was performed to evaluate the cell viability at different light doses. (B), the percentage of S462 cell viability after the treatment of different concentration of doxycycline. (C) Left panel shows the percentage of cell viability under PDT alone and in combination with doxycycline (10- and 50- μg/mL) under the light dose of 8 J/cm². The contour connecting every point (d1, d2) in the isobologram bows inwardly, which indicates a Loewe synergy between the treatment of ALA-PDT and doxycycline (right panel).