APOL1 and focal segmental glomerulosclerosis: APOL1 risk variant expression in transgenic mice of a FSGS model (APOL1; Podocin-rtTA; NFATc1nuc) were more susceptible to doxycyclin induction as their wildtype littermates (WT; Podocin-rtTA; NFATc1nuc) and developed podocyte loss and mesangial matrix expansion.