As summarized in Fig. 7P, in this study, we have identified that hSPAR/hSPAR-C exhibits robust inhibitory effects on mTOR signaling activation through coordinate regulations by promoting the stability of P27KIP1 protein in the cytoplasm and inducing glutamine deprivation-dependent lysosomal-localization of P27KIP1 specifically in cancer cells. This evidence concerns the gene CDKN1B and cancer.