In leukaemic cells, AFF4-depleted SEC can result in an obvious reduction in MLL chimaera target gene expression.20 AFF4 can activate HIV-1 proviral transcription and transcription elongation factors, which are dispersed along a flexible AFF4 scaffold and can be recruited by the HIV-1 protein Tat.41 In head and neck squamous cell carcinoma cells, AFF4 can improve tumour initiation and tumorigenesis capability though SOX2.42 Previous research found that Aff4/Af5q31-null mice exhibited azoospermia, suggesting a nonnegligible effect on Sertoli cells. This evidence concerns the gene KMT2A and head and neck squamous cell carcinoma.