In addition, loss‐of‐function mutations have been identified in well‐described tumour suppressors that affect various signalling pathways, including cell cycle processes (TP53, RB1), PI3K/mTOR signalling pathway (PTEN, TSC1) and mitogen‐activated protein kinase (MAPK) signalling pathway (NF1). The gene discussed is RB1; the disease is neoplasm.