SMPD1 and malignant colon neoplasm: Indeed, previous studies have shown that single-dose exposures <8 Gy in CT26 colon cancer (Zhu et al., 2015) and MCA/129 fibrosarcoma (El-Kaffas et al., 2018) cells in vivo are not able to exhibit the cell-killing effect in an ASMase-dependent fashion.