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. 2024 May 10;101(1):4–20. doi: 10.1111/php.13957

FIGURE 6.

FIGURE 6

The updated taPIT protocol selectively kills EGFR‐positive cells and avoids non‐specific killing of EGFR‐negative cells. In conventional taPIT experiments, the light dose was administered immediately after PIC removal and washing. In updated taPIT experiments, the light dose was administered following 2 h of post‐wash incubation. (A) Conventional taPIT dose–response, and (B) updated taPIT dose–response of an EGFR‐negative cell line 3T3. A PIC dose of 300 nM BPD equivalent was used for the conventional taPIT experiment (~50 nM cetuximab). (C) Conventional taPIT dose–response, and (D) updated taPIT dose–response of another EGFR‐negative cell line CHO‐K1. 250 nM BPD equivalent PIC was used for the conventional taPIT experiment. (E) Conventional and updated taPIT dose–response of an EGFR‐positive cell line OVCAR5. 250 nM BPD equivalent PIC was used for both experiments. (F) Relative EGFR expression levels of 3T3, CHO‐K1, OVCAR3, OVCAR5, and A431 cell lines determined by flow cytometry. (G) Updated taPIT dose–responses of 3T3, CHO‐K1, OVCAR3, OVCAR5, and A431 cell lines. Conventional taPIT protocol killed EGFR‐negative cell lines as well, but the updated taPIT protocol only killed EGFR‐positive cell lines. The cytotoxicities were in agreement with the EGFR expression levels when the updated taPIT protocol was followed. Three replicates were used for flow cytometry, and four to nine replicates were used for taPIT experiments. Results are mean ± standard deviation.