AZD1480 only reversed CD24 in MDA-MB-134, not in CAMA1, while UC2288 showed a reversal trend in both CAMA1 (p = 0.059) and MDA-MB-134 (p = 0.096).The combined use of FACS analysis and qPCR for assessing stemness features, along with mammosphere culture assays, affirmed that FGF ligands could enhance stemness-like traits through FGFR1-p21 regulation via the JAK-STAT pathway, contributing to stemness-like characteristics in FGFR1-amplified ER + breast cancer cells. Here, ESR1 is linked to breast cancer.