PIK3CA and urinary bladder cancer: Additionally, among the three different m6A methylation patterns in bladder cancer, there were differences in gene mutations (51) for TP53, RB1, FGFR3, CDKN2A, ERBB2, and PIK3CA. Patients had a greater number of FGFR3 and CDKN2A mutations in Cluster 1 than in Cluster 2 or Cluster 3, while the converse was true for TP53 mutations.