In collapsing FSGS, the reduced expression of Krüppel-like factor 4 (KLF4) in podocytes triggered IL-6 release into the supernatant, which stimulated PEC activation via signal transducer and activator of transcription 3 (STAT3) pathway (Estrada et al., 2018). Here, STAT3 is linked to focal segmental glomerulosclerosis.