STAT3 and breast cancer: With respect to the Stat pathway, Elizalde et al.97,98 reported MPA significantly upregulated P21CIPI and CCND1 expressions in T47D breast cancer cells, resulting from assembling the Stat3/ErbB-2/PR transcriptional complex, where Stat3 bound to the P21CIPI proximal promoter while both ErbB-2 and PR functioned as Stat3 co-activators.