LRRK2 R1441G knock-in cells, as well as iPS cells derived from PD patients carrying the LRRK2 G2019S mutation, exhibited defects in ciliation and a decrease in the Shh signaling, indicating that the abnormal activation of LRRK2 blocks the Shh signaling in cells [42]. This evidence concerns the gene LRRK2 and Parkinson disease.