POMC and neoplasm: To determine the effects of the USP8-P681Q variant that we had found in our patient in murine corticotroph tumor cells on POMC transcription, we transfected the plasmids expressing USP8-WT, USP8-P681Q, and the hotspot variant USP8-S718P into AtT20 cells individually (Relative USP8 mRNA expression: Control vs. USP8-WT vs. USP8-P681Q vs. USP8-S718P, 1 ± 0.03 vs. 810 ± 57 vs. 625 ± 47 vs. 818 ± 17, Fig. 3A).