To study the interaction between IGF-1R and intact IGF-1 or T-IGF1, the activation of IGF-1R by IGF-1 was first investigated in different human lung cancer cell lines, including CL1-0 (a well-studied lung ADC cell line (27)), NCI-H520 (a lung SCC cell line), NCI-H460 and NCI-H661 cells (two large-cell carcinoma cell lines). The gene discussed is IGF1; the disease is lung carcinoma.