Homozygous Celf1−/− mice are not viable on 129SvPas nor C57BL/6N pure backgrounds.

We separately crossed heterozygous Celf1+/− mice from two different inbred strains (129SvPas and C57BL/6N) to obtain F1 litters. We genotyped pups found dead after birth, and pups alive at 8–10 dpp. We show here the number of −/− and other (+/+ and +/−) pups. P-values for agreement with the Mendelian ratio (1/4 of −/− pups) were calculated by chi2 test for goodness of fit taking into account either only the live pups or all the pups.