PIK3CA and cancer: We extend Gerlee's model by (i) considering six cell types (normal tissue cells NTC, mutated normal tissue cells MNTC, normal stem cells NSC, mutated normal stem cells MNSC, cancer stem cells CSC, tumor cells TC, and empty cells) (ii) including transit amplifying cells (iv) including four phenotypic actions (proliferation, quiescence, apoptosis, differentiation) (v) including 10 gene expression levels for TP53, TP73, RB, TP21, T16, EGFR, CCDN1, MYC, PIK3CA, and RAS.