TRPV1 and hereditary clear cell renal cell carcinoma: However, TRPV1 mRNA levels are upregulated in the U373 glioblastoma line, high-grade astrocytes, “brain tumors,” and the RT4 renal cell carcinoma line; likewise, upregulated TRPV1 protein expression is observed in the U373 and RT4 cell lines (Table 2).