Analysis of patient JAK3 protein and mRNA expression levels. (A) Lysates of EBV-transformed B cells from a healthy control ([lane 1]) and 7 SCID patients [lanes 2-8] were electrophoresed and immunoblotted with anti-JAK3 Ab (top blot). The membrane was stripped and reprobed with anti-STAT5A antiserum (bottom blot) to assess sample loading. (B) EBV-transformed B-cell RNA samples from a healthy control (lane 1) and SCID patients 1 to 6 (lanes 2-7) were analyzed on a Northern blot sequentially hybridized with ³²P-labeled JAK3 (top blot) and actin (bottom blot) probes. (C) EBV-transformed B-cell cDNA from a healthy control (lane 1) and SCID patient 7 (lane 2) were PCR amplified using JAK3- or GAPDH-specific primer pairs and template concentrations previously determined to yield similar quantities of control and patient GAPDH product. Ethidium-stained reaction products are shown.