ASAH1 and neoplasm: Condamine et al. (2014) found that MDSCs in tumor-bearing mice had increased apoptosis and poor survival, which was associated with the increased expression of TRAIL receptors (TRAIL-Rs; Condamine et al., 2014). Subsequent further study showed that MDSCs from cancer patients exhibited higher ER stress levels, and the expression of TRAIL-Rs was upregulated, while targeting TRAIL-Rs improved the anti-tumor effect. In contrast, the acid ceramidase inhibitor LCL521 induced MDSCs death through an apoptosis-independent mechanism death (Liu et al., 2016).