As TOP1 shows no significant oscillations at the gene expression level in CRC HCT116 cell lines, and the corresponding protein TOP1 is reported as constant in the Caco-2 human colorectal cancer cell line13,14, we removed TOP1 from the transcription-translation network, and assumed a constant TOP1 protein expression for the PK-PD model part. The gene discussed is TOP1; the disease is colorectal carcinoma.