We have cloned a murine homologue of the human Mcl1/EAT gene, a Bcl-2 related gene. Sequence analysis revealed that murine Mcl1/EAT (mMcl1/EAT) has three Bcl-2 homology domains, two PEST sequences, and immediate response boxes (IRB). The presence of IRB indicates that mMcl1/EAT is an immediate-early gene. mMcl1/EAT increases dramatically with exposure to retinoic acid in murine embryonal carcinoma cell lines (F9 and PCC3) as well as embryonic stem cells, both of which are models of early embryogenesis.