Checkpoint (two meanings)

Immune checkpoints are receptor-ligand pairs such as PD-1 with PD-L1, CTLA-4 with CD80 and CD86, LAG-3, TIM-3 and TIGIT that hold T cells and NK cells back; the drugs are antibodies that block them (or, for co-stimulatory receptors, agonists that press them). Cell-cycle checkpoints are the G1/S, G2/M and spindle assembly gates governed by cyclin D-CDK4/6 and RB, ATR-CHK1-WEE1, and MPS1, BUB1 and Aurora B, with the DNA-damage response behind them; the drugs are small molecules such as palbociclib, olaparib and azenosertib. The two families share a word and nothing else; OnCo keeps a hub for each, with every member, its partner, where it is expressed and the drugs against it.