SMAD-mediated TGFβ/BMP signaling has also shown to be associated with the primary cilium37–41, for example during differentiation of mouse carcinoma stem cells (P19.CL6 cells) into cardiomyocytes where TGFβ-mediated phosphorylation of SMAD2/3 at the ciliary base is required for the process of cardiomyogenesis40. Here, TGFB1 is linked to carcinoma.