UPF3A and embryonal carcinoma: Through generating a conditional KO mouse model of Upf3a with a traditional gene targeting strategy, Shum et al found UPF3A represses NMD in mouse pluripotent cells (P19 embryonic carcinoma cell), tissue-specific stem cells (neural stem cells and olfactory sensory neuronal precursors), somatic cells (mouse embryonic fibroblasts and neurons), and human 293T cells.