Downstream, we observed that impaired trafficking of phosphorylated JNK upon loss of MAPKBP1 and pharmacological disassembly of the JNK-target, actin, restores ciliary length in patients with NPHP20. Overall, MAPKBP1-associated molecular alterations appeared to be relatively modest, in line with late onset kidney function decline in patients with NPHP20. The gene discussed is MAPK8; the disease is nephronophthisis 20.