SHH and cancer: Although primary cilia are lost in a wide range of cancer types, as described in the section below, primary cilia can also promote tumor progression in different types of cancer, including medulloblastoma, basal cell skin cancer, and basal‐like breast cancer.2, 147, 148, 149 Medulloblastoma comprises four major subgroups: sonic hedgehog (SHH), WNT, group 3, and group 4.150, 151, 152 The SHH subgroup accounts ≈30% of all cases.