TP53 and small cell lung carcinoma: When plated onto organotypic plugs preconditioned with telomerase-immortalised human fibroblasts (TIFs), H1229 non-small cell lung carcinoma cells (which do not express p53) (H1299-p53−/−) were poorly invasive, with most cells residing in the upper portion of the plug 10 days after plating (Fig. 1a, d).