To test whether p53 regulates SALL2 gene transcription, the various SALL2 promoter luciferase reporter constructs were individually co-transfected with a p53 expression vector into 293T cells (constitutively express the simian virus 40 large T antigen, which binds to p53 and prevents it from activating transcription [30–33], but does not decrease the stability of p53 [34]), p53-null MEFs, or H1299 lung cancer cells (have a homozygous partial deletion of the TP53 gene and as a result, do not express the tumor suppressor p53 protein [35]). Here, TP53 is linked to lung carcinoma.