RSPO1 and lung cancer: In contrast, PDT-LUAD#19 lung tumoroids (TPM3-ROS1; TP53K120Sfs*3) grew only in AO media but not in other media for the long term, indicating along with the data in Fig. 4 that R-spondin 1, SB 202190 and/or nicotinamide in the AO media are essential to culture PDT-LUAD#19 lung tumoroids, which suggests that tumorigenic pathways influenced by R-spondin 1, SB 202190 and/or nicotinamide might be possible therapeutic targets for ROS1 tyrosine kinase inhibitor-resistant lung cancers.