ESR1 and breast cancer: Moreover, ALDH18A1 and Glutaminase protein levels are higher in high proliferative estrogen receptor positive (ER+) /human epidermal growth factor receptor negative (HER2−) (Luminal B) compared to low proliferative ER+/HER2− (Luminal A) tumor cells, thus suggesting that the Glutamine-Proline axis is a poor prognosis marker in BC (28).