RNASE1 and neoplasm: Since higher stability is a critical prerequisite for tumor markers, we next tested the stability of PART1 in serum exosomes by exposing exosomes to different conditions including incubation at room temperature (0, 3, 6, 12 and 24 h), RNase A digestion, and low (pH = 1) or high (pH = 13) pH solution for 3 h at room temperature.