look for a published microarray or RNA-seq experiment with the same type of cells. Look for genes that are NOT up- or down-regulated. Verify in your cells with qPCR that such genes did not change in your experiment. If the gene(s) were invariant, they can be used as housekeeping control.

There are many housekeeping genes available for use as reference gene. Try actb or rps18.

Hello Maria

You can try using Rpl13a or Sdha as housekeeping genes. Please refer to the research article below for more information.

Article Validation of housekeeping genes for quantitative real-time ...

Best Wishes.

.

https://erj.ersjournals.com/content/38/Suppl_55/p3805

"Identification of stable housekeeping genes for real-time PCR in human pulmonary fibroblasts"

Hope this paper will give you more insight.

Masuma