UPP1 and Patent ductus arteriosus: Being the most upregulated, we tested PGM2 by western blot and found it to be expressed in most PDA cells but uncorrelated with UPP1 (Extended Data Fig. 4i). Inhibition of  the three genes using short interfering RNA (siRNA) showed that only PGM2 knockdown suppressed the uridine-mediated rescue of metabolic activity following glucose deprivation (Extended Data Fig. 4j–l).