ACTA1 and cancer: Moreover, we found that in the pretreatment biopsy tissues, α-SMA expression in the cancer-associated stroma was correlated with ERβ expression in BCa tissues (Fig. 1d, Pearson correlation coefficient = 0.52, P < 0.01), and this correlation was much stronger in the RC tissues after NAC treatment (Fig. 1d, Pearson correlation coefficient = 0.70, P < 0.001).