In order to check the effectiveness of SMO inhibition in the treatment of three types of cancers we performed the model simulation by only inhibiting the SMO expression levels (in-silico treatment of cancer cell with SMO inhibitors) and found that SMO inhibition alone was not able to down regulate the activity of some onco-proteins such as GLI1, GLI2, GLI3_A and also the output proteins related to these. This evidence concerns the gene SMO and cancer.