Model for homeostatic cell-cycle control of PC differentiation. PCs are generated via the GC reaction or the extrafollicular response in a TD response. iPCs are transient intermediates between aBCs and PCs and consist of 3 populations: Blimp-1−/Bcl-6+, Blimp-1+/Bcl-6+, and Blimp-1+/Bcl-6−. p18 and Noxa mediate cell-cycle control of iPC homeostasis during differentiation to end-stage PCs.