SOX9 and pachyonychia congenita: IF staining for GRK3 alone and dual staining of GRK3/SOX9 in representative PC samples are shown in Fig. 1I and Supplementary Fig. 1B. Furthermore, in 4 pairs of the primary tumors and PC cells, each pair from the same patient, GRK3 expression was higher in 3 PC samples (75%) than in the corresponding primary tumor (Supplementary Fig. 1C).