ESR1 and breast cancer: As both ANXA1 and CALD1 have been reported to be expressed in basal-type breast cancers, which are characterized by downregulation of ER and its responsive genes [44], and the fact that only a minority of the ER positive tumors that were captured in the TMA displayed expression of these markers, it is possible that these proteins may enable further stratification of ER positive breast malignancies.