Hodgkin cell lines and primary HRS tumor cells are characterized by high constitutive ATF3 expression. (A) ATF3 mRNA and protein expression in Hodgkin and non-Hodgkin cell lines was determined by Northern (NB) analysis and Western (WB) blot analysis, respectively. As loading controls, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) mRNA and α-tubulin protein expression were included. (B) Immunostaining for ATF3 in primary tissue samples (cHL, classical Hodgkin lymphoma; LPHL, lymphocyte-predominant Hodgkin lymphoma; ALCL, anaplastic large cell lymphoma).