During BC progression, squamous differentiation (SqD) was often obsearved in advanced bladder cancer. Molecular basal subtypes is relatively associated with SqD than luminal subtypes. In luminal subtypes, TFAP2A expression is repressed by PPARɣ receptor. On the other hand, TFAP2A is expressed in basal subtypes due to the loss or malfunction of PPARɣ in terms of the capabilities to repress TFAP2A. TFAP2A upregulates TP63 expression and cooperates to induce SqD with TP63 as well as other factors in basal subtypes of human BC.