RARB and cancer: With the exception of three clusters of NRs representing NR classes I (cluster I: RORC, VDR, PPARA, NR1D1, THRA, RORA, NR1H3; cluster II: RARB, PPARG, THRB) and III (cluster III: ESR1, PGR, AR, ESRRG), NR class was not a good determinate of NR expression patterns in the different cancer types.