Figure 1.

Expression of Rb in ALCL cell lines. A: Immunoblot showing three cell lines that express total Rb, with Karpas 299 and SU-DHL-1 cells having higher levels compared with JB-6 cells. Underphosphorylated Rb was detected at low levels in all three ALCL cell lines. Similar results were obtained for the SR-786 cell line (data not shown). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was included as a control for protein load and integrity, and its levels are similar among all three ALCL cell lines. B: Immunoblot showing the levels of total and underphosphorylated Rb protein after serum starvation of SU-DHL-1 cells. Densitometry showed that the underphosphorylated Rb/total Rb ratio was higher in cells treated with RPMI and only 1% of FBS (serum starvation) at 48 and 72 hours compared with control cells.