Slfn5 expression does not differ appreciably with postnatal age in the intestine, liver, or lung. Relative Slfn5 expression, as determined by quantitative reverse-transcription polymerase chain reaction, is essentially the same in the fetal (E20) and postnatal (P0, P1, P5) samples in the intestine and the liver. The P0 spike observed in the lung is not maintained on subsequent days. The data support a specific role for Slfn3 in postnatal intestinal epithelial development. *P < .05 by one-way analysis of variance comparing P0 with P1 and P5 (n = 5).