Some years later, Davidson et al. [87] characterized the expression of NGF, NGFR/p75NTR and phospho-TrkA (p-TrkA activated receptor) during the progression of breast carcinoma from primary tumor to pleural effusion in sections from malignant pleural effusions from breast cancer patients and the corresponding solid tumors. The gene discussed is NTRK1; the disease is Pleural effusion.