Most modifications to phenothiazine ring G2, such as the branch substitutions (6–7), or replacement with other rings (9–13, S19–S22), led to the decreased activity in p53 induction, with the exception of that the substitution of sulfur in the G2 region by methylene (1→8) showed greater potentcy than compound 1 in both p53 induction and cancer cell inhibition. Here, TP53 is linked to cancer.