When his doctor told him that he had leukemia, all Casey Isreal could think was that there'd been a mistake.

He'd just turned 40, and although he'd been losing weight and feeling weak, he'd been so busy with his sales job, his wife and his two young children at home in Mount Airy that he kept canceling doctor's appointments last summer.

"You're just going along in life, just happy-go, cutting grass and stuff," he said. "You really don't think about a sickness or illness coming on."

Now, after months of chemotherapy, he knows all too well that he can't count on a bone-marrow transplant if the cancer returns. It could be difficult to find a match, most likely someone of his race, whose healthy blood cells wouldn't be rejected by his body. "I'm African American," he said, "and unfortunately we're very much underrepresented."

There are 6 million people on the National Marrow Donor Program registry. Fewer than 8 percent are African American. (African Americans make up 12 percent of the population.)

So the donor program, along with members of the Congressional Black Caucus and the National Conference of Black Mayors, has launched a multi-city campaign to increase the diversity of volunteers and recruit 150,000 more African American donors this year.

Yesterday afternoon at Beltway Plaza Mall in Greenbelt, Gina Boyd, a donor recruitment specialist with the National Institutes of Health Marrow Donor Program, and Tania Scinto, a donor coordinator also with NIH, displayed pamphlets and a big sign that said "You Have the Power to Save a Life."

Most people barely gave them a second glance.

"It's hard," Boyd said. "There's a lot of fear, a lot of myths, especially in the minority community, which we're trying to dispel. Native Americans and blacks can have mistrust of the government" and medical research, she said.

And many people just don't know how great the need is.

Isreal didn't.

Boyd hopes events like yesterday's make people think. "Studies show it takes five times to reach a person," she said, watching people walk by eating big cookies on sticks and talking on cellphones. "If they hear it today, at church, see a commercial -- maybe the fifth time they're ready to sign up."

D.J. Mack, a maintenance worker at the mall, put down his broom for a moment. "I think it's a very good thing they're doing," he said. "You never know."

But he didn't sign up. "Maybe," he said, walking away. "Maybe."

Margaret Albright of Seat Pleasant has been thinking about it for a while. She has seen friends and relatives search for donors. And she knows that more black volunteers are needed. She sat eating some popcorn. "Every day is a blessing," said Albright, 58.

Then she stood up and told Scinto that she was ready.

She filled out paperwork and then rubbed cotton swabs inside her mouth for a sample. If needed, she might have additional testing and then a more invasive procedure to harvest her marrow.

Isreal has his bone marrow tested every two months and his blood tested every month to see if the acute myelogenous leukemia has come back.

He's just started working again. It feels great, he said, to be on the job again and to be able to play with his 5-year-old daughter and 2-year-old son on the swing set outside and not have to explain that daddy's been sick and can only be indoors or at the hospital. It feels great not to burden his wife with so much anymore, or to worry about whether they'll be able to afford their house.

He still wakes up in the middle of the night and thinks about wanting to see his children grow up. And he wonders whether, if the cancer does come back, a matching donor will be there.