CD74 and breast cancer: Besides its expression on immune system cells, CD74 has also been expressed in a variety of cancer cells, including thyroid carcinoma [17], bladder cancer [18], chronic lymphocytic leukemia (CLL) [19], multiple myeloma (MM) [20], breast cancer [21], gastrointestinal cancers [22], non-small cell lung cancer (NSCLC) [23], renal cell carcinoma (RCC) [24], prostate cancer [25], pancreatic cancer [26], and glioblastomas [27].