BIRC5 and infection: This hypothesis is corroborated for the preNeu N1 subpopulation, as the Fig. 3a heatmap shows an infection-triggered expression of the apoptosis inhibitor Birc5 (survivin) and the proliferation marker Mki67. Simultaneously, the mature N4 subpopulations express high levels of the cell survival regulator Mcl1, as well as Csf3r, coding for the G-CSF receptor.