| Biochemistry analysis demonstrated that POU transcription factors ( Oct 1 and Brn 2 ) bind to the specific binding elements of both sites 1 and 2 to stimulate Pax 3 gene expression , whereas the TALE homeodomain containing proteins ( Pbx and Prep 1 ) bind with the core binding sequences of sites A and B to repress the expression of the Pax 3 gene in B 16 cells . . ^^^ |