The loss in activity of cell-cycle repressors (MAF and MAFB) and gain of BHLHE40 may represent a more proliferation-permissive state,27,28 consistent with enhanced LCM proliferation in nematode-infected C57BL/6 mice relative to BALB/c mice.7 Thus infection of C57BL/6 but not of BALB/c mice leads to a large expansion of M(IL-4) activated LCMs. Here, BHLHE40 is linked to infection.