Pit-1 regulates MMP-1 and MMP-13 expression. (A) MCF-7 cells were transfected with the pRSV-hPit-1 overexpression vector and 48 hours later a real-time PCR was carried out to evaluate MMP-1, MMP-13, and Pit-1 mRNA expression. (B) Western blot of MMP-1, MMP-13, Pit-1 and β-actin in MDA-MB-231 cells 48 hours after Pit-1 overexpression or Pit-1 knockdown. (C) Densitometric quantitation of three different blots. Values expressed as mean ± SD represent relative Pit-1, MMP-1, and MMP-13 protein expression in relation to β-actin values. MMP-1, matrix metalloproteinase-1; MMP-13, matrix metalloproteinase-13; Pit-1, POU class 1 homeobox 1.