STAT3 and nonpapillary renal cell carcinoma: In this context, previous studies from our group brought to light the role of the signal transducer and activator of transcription 3 (STAT3) in ccRCC by demonstrating that its activation resulted from the overexpression of the human hepatitis A virus cellular receptor 1 (hHAVCR1), also known as kidney injury molecule 1 (KIM1)12.