Genetic inhibition of HMOX1 in the UOK 262 cell line leads to decreased cell viability after transduction with three out of four tested shRNA. UOK 262 cell line was transduced with lentiviral vectors encoding four shRNA sequences against HMOX1 transcript and with one, non-specific scrambled shRNA. (A) Representative pictures of UOK 262 cells 3 days after transduction, scale bar: 100 µm, upper row—bright field, lower row—fluorescence. (B) qRT-PCR results of HMOX1 silencing level in UOK 262 cell line after transduction with HO-1 shRNA sequences and scrambled shRNA presented as relative fold change (mean ± SD). (C) Microscopic images both in the bright field (upper part) and under fluorescence (lower part) 14 days after transduction with lentiviral vectors encoding shHO-1 and scrambled sequence showing decreased cell number in shHO-1 B-D. (D) MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) viability assay after several time-points (9–14 days) from transduction, presented as the percentage of scrambled shRNA (mean ± SD). (E) BrdU (bromodeoxyuridine) incorporation assay performed 7 and 9 days after transduction, presented as the percentage of scrambled shRNA (mean ± SD). * p < 0.05 vs. scrambled sequence, Student’s t-test; $ p < 0.05 vs. previous tested day of the assay, ANOVA test.