CD19 and lymphoma: Strikingly, the selection against cells expressing the hCD4 reporter (i.e. selection against cells that had deleted the Mcl-1fl allele) was clearly more potent in Eμ-Myc;Rag-1-Cre;Mcl-1fl/+ lymphoma cells than in those from the Eμ-Myc;CD19-Cre;Mcl-1fl/+ mice (compare data in Figures 2c and 5a).