Shows no ribosome-associated and endoribonuclease activities. Displays polysome-associated endoribonuclease activity towards mRNAs and rRNAs (PubMed:25996083). May play a role in RNA surveillance pathways by recognizing stalled ribosomes and triggering endonucleolytic cleavage of aberrant mRNAs (Probable). Cleaves RNAs in a magnesium-, manganese-dependent and ATP-independent manner (PubMed:25996083). Involved in correct maturation of megakaryocytes and especially important for proplatelet extension (By similarity). C-terminally truncated SLFN14 endoribonuclease: Requires manganese and magnesium for its endoribonuclease activity. Associates with ribosomes in an ATP-independent manner (PubMed:25996083). Detected in reticulocytes (at protein level) (PubMed:25996083).