Foetal bovine serum (fbs)

MDA-MB-231, MCF-7, BT-549, and SK-BR-3 human breast cancer cells were obtained from the American Type Culture Collection (ATCC, Manassas, VA). MDA-MB-231 cells were cultured in Leibovitz’s L15 medium and BT-549 cells were cultured in RPMI 1640 medium, MCF-7 cells were cultured in DMEM, and SK-BR-3 cells were cultured in McCoy’s 5A medium (Thermo Fisher, Waltham, MA), supplemented with 10% foetal bovine serum (Cellmax, China), penicillin (100 units/ml), and streptomycin (100 µg/ml). All cells were incubated at 37°C in a humidified atmosphere of 5% CO₂. None of the cell lines were contaminated with mycoplasma.

NIH/3T3 and 293T cells were cultured in DMEM (CGM101.05; CellMax, Lanzhou, China). JEG3 cells were cultured in EMEM (11700; Cary, Huzhou, China). HTR8/SVneo cells and Ishikawa cells were cultured in RPMI medium (C11875500BT; Thermo Fisher Biochemical, China). Cells were cultured at 37°C in a 5% CO₂ atmosphere, and all culture media were supplemented with 100 U/ml penicillin and streptomycin (BL505A; Biosharp, Beijing, China) and 10% foetal bovine serum (CellMax, Lanzhou, China).
KRT18 antibody was purchased from Novus Biologicals (NPB2-67370; Littleton, CO, USA). Phalloidin was purchased from Thermo Fisher Scientific (A22284; USA). KRT18 fusion protein (Ag1260) and E-cadherin fusion protein (Ag15085) were purchased from Proteintech (Wuhan, Hubei, P.R.C.).

The mouse anterior pituitary corticotroph adenoma cell line AtT‐20/D16v‐F2 was purchased from ATCC, while COS‐7 cell line was purchased from Cell Bank of Type Culture Collection of Chinese Academy of Sciences. AtT‐20 cells and COS‐7 cells were cultured in DMEM (ATCC, 30‐2002) media supplemented with 10% foetal bovine serum (Cellmax, Peking, China) and penicillin‐streptomycin. The cells were incubated at 37°C and 5% CO₂ atmosphere. Bexarotene, ATRA, and dexamethasone (DEX) were obtained from Selleck and stored at −80°C. Corticotropin‐releasing factor human (CRH) was obtained from MCE and stored at −80°C.