The special relevance of the mSWI/SNF complexes in cancer, reported in the early 2000s and in continued increase in the last two decades, is reflected in the fact that ~ 20% of human cancers harbour deleterious mutations in at least one mSWI/SNF subunit, a mutation rate comparable to that of well-known driving tumour suppressors such as TP53 and PTEN [18]. The gene discussed is PTEN; the disease is cancer.