SAPS1 is a regulatory subunit of the PP6 phosphatase. There are 3 human SAPs (sit4-associated proteins), SAPS1, SAPS2, and SAPS3. The human SAPs are related to SAPs found in yeast that associate with the sit4 phosphatase which is the homolog of human PP6 phosphatase. In yeast sit4 and its associated SAPs are involved in a variety of processes which include transcription, translation, bud formation, glycogen metabolism, ion homeostasis, and telomere function. SAPS1 mRNA has been found to be overexpressed in hepatocellular carcinoma, metastatic liver tumors, and lymphoblastic leukemia.