(A) Microarray analysis of MAPK pathway signature genes in untreated transgenic C3(1)-SV40TAg mammary glands (n = 3) at progressive disease stages. (B) The effect of bi-weekly siHoxA1 injections on protein expression of MAPK components, ERK1/2, SRC, IER3, KRAS, PCNA and GRB2, in mammary glands of 21-week old transgenic animals (n = 3) compared with injection of non-targeting control siRNA (siNT) (n = 3).