CDK7 plays a conserved role in differentiating MCCs. (A–C) Confocal pictures of A6-MCI cells treated with DMSO (control, A) or with CDK7 inhibitors (B and C) and stained for Ac-α-Tub (cilia), centrin (centrioles), and ZO1 (tight junctions). (D) Graphs displaying the percentage of cells with or without centriole staining and the percentage of cells with or without cilia staining. n = 521 (DMSO), 526 (LDC4297), and 809 (YKL-5-124) cells. SEM is shown. Data were collected from three independent experiments. Fisher’s exact test: P <2.2e−16 (***) for LDC4297 and YKL-5-124 vs DMSO. (E–G) Confocal pictures of epidermis from Xenopus embryos treated with DMSO (control, E) or with CDK7 inhibitors (F and G) and stained for Ac-α-Tub, centrin, and ZO1. (H) Graphs displaying the percentage of cells presenting defects in centrioles or cilia. n = 341 (DMSO), 337 (LDC4297), and 368 (YKL-5-124) cells. SEM is shown. Data were collected from three independent experiments. Fisher’s exact test: P < 2.2e−16 (***) for LDC4297 and YKL-5-124 vs DMSO. (I–K) Confocal pictures of epidermis from Xenopus embryos injected with GFP (control, I), Cdk7 translation- (TB MO, J), or splice- (Spl MO, K) blocking morpholinos and stained for Ac-α-Tub, centrin, and ZO1. (L) Graphs displaying the percentage of cells presenting defects in centrioles or cilia. n = 699 (GFP), 826 (Cdk7 TB MO), and 673 (Cdk7 Spl MO) cells. SEM is shown. Data were collected from 15 embryos from three independent experiments. Fisher’s exact test: P < 2.2e−16 (***) for MO TB and MO Spl vs control. (M–O) Confocal pictures of hAECs treated with DMSO (control, M) or with CDK7 inhibitors (N and O) and stained for Ac-α-Tub, centrin and ZO1. (P) Graphs displaying the percentage of cells with or without centriole staining and the percentage of cells with or without cilia staining. n = 1551 (DMSO), 732 (LDC4297), and 578 (YKL-5-124) cells. Data were collected from three independent experiments. Fisher’s exact test: P < 2.2e−16 (***) for LDC4297 and YKL-5-124 vs DMSO. Scale bar: 15 μm (A–C, E–G, I–K, and M–O).