CD63 and cancer: In the cohort of 52 evaluable samples from patients with different cancer histologies (e.g., serous, endometrioid, clear cell, carcinosarcoma, mucinous, mixed) and diverse treatment histories, circulating basophils from 49/52 (94%) of samples responded to one or more of the three stimuli (anti-FcεRI, anti-IgE, fMLP) by up-regulating cell surface CD63 (Figure 2C,D and Table S3).