ESR1 and breast cancer: We performed in situ VCHi-C and PCHi-C [16, 18] in 2 non-tumorigenic breast cell lines (B80T5, MCF10A), 2 estrogen receptor-positive (ER+; MCF7, T47D) breast cancer cell lines, and 2 ER− (MDAMB231, Hs578T) breast cancer cell lines.