CTSD and breast carcinoma: Although the levels of LAMP2, RAB7, ULK1, and BECN1 are unaltered in Ctsd-deficient mice, Ctsd-deficiency in a mouse breast cancer model reduces the localization of mTORC1 to lysosomes when cells are placed in amino acid-limiting conditions (Figure 2) (Ketterer et al., 2020; Iwama et al., 2021).